Twenty-four shows that started life at the Old Globe Theatre in San Diego have gone on to Broadway since “Into the Woods” established it as a headquarters for out-of-town tryouts back in the late 1980s. That would be all the reason anyone needs for the new stage musical adaptation of Cameron Crowe’s 2000 film “Almost Famous” to have its world premiere there in late September. But Crowe has some even better reasons — like the fact that most of the events in the film and show transpired within a few miles’ radius. When the Old Globe is mentioned in the musical, you might assume it’s a gag just for locals — if you don’t remember that the line, like much of the book he wrote for the new musical, is straight out of his semi-autobiographical screenplay.

“I just figure Broadway, if it happens, is a gift,” says Crowe, looking all too relaxed as he loiters outside the theater in shorts and a T-shirt, a few hours before what should be the nerves of an opening night. “But if this is everything. … When I got off the exit coming here a month ago, I thought, this is where we should be, and we’re getting here at the right time. Because it’s not a New York story. It’s a San Diego story. We lived [virtually] across the street! I met Lester Bangs a mile and a half away, at Seventh and Ash. It really feels right, before they tear down the Sports Arena [the endangered site of the story’s early encounters between rockers, groupies and a teen rock journalist]. It’s built for here, which makes it personal. But,” he adds, thinking to the Great White Way, “if the personal is the universal, great!”

Presumably, the show’s actors, crew and investors don’t exactly share Crowe’s “San Diego is everything!” attitude. But they probably don’t have too much to worry about. Los Angeles Times critic Charles McNulty, usually a harder sell, gave the show an uncharacteristically gushy review, saying that although driving down to San Diego for prospective Broadway plays rarely pays off, “Almost Famous” is “as shimmering as a stadium of lighters during a Led Zeppelin encore” and “seems destined to conquer Broadway.” Given critical and audience reactions like that, no one involved with the show seems to think it needs an intermediary run to get the kinks out after it closes in on Oct. 27; the word is that they’re just waiting for an open theater. A Sony MasterWorks cast album has already been slated. For a show about growing pains, “Almost Famous” looks to be getting preternaturally fast-tracked without any.

But what will be on that cast album? That was the biggest hiccup in the show’s development. “Probably eight years ago, I started taking it seriously,” Crowe says, “and there were a couple versions. One was a jukebox version I was messing around with, which definitely at a certain point didn’t feel right.” Three years ago, one of this show’s producers, then-Sony exec Lia Vollack, had a meeting with esteemed British dramatic director Jeremy Herrin — a Shakespearian specialist who’s spent a lot of time at that other Globe, in London — and asked him to look through a list of 700 film titles the studio had the rights to, and he immediately singled out “Almost Famous.” Herrin and Crowe got on, well, famously. They brought in Tony and Pulitzer winner Tom Kitt (“Next to Normal”) to write the music and co-write lyrics with Crowe, which meant that it was no longer a jukebox musical.

Or was it? “We knew people would still want to hear [Elton John’s] ‘Tiny Dancer’” — the movie’s centerpiece bus sing-along — “so let’s track back from there,” says Herrin. “The best thing was to do a blend, and to encourage Tom to write to the era and to orchestrate songs from the era and make them dramatic.” The result is a compromise, about 15% jukebox (think Allmans, Zeppelin, Skynyrd, Joni, Bowie) and 85% original score. “We just thought that this would be our contribution to musical theater: getting ‘Highway Star’ onto a Broadway stage,” quips Herrin, referring to the use of an old Deep Purple FM staple that has become an Act 1 highlight.

Crowe says producers didn’t get a single turn-down on the existing songs they wanted to license. “Elton said, ‘You better use “Tiny Dancer”!’ I was like, ‘You bet!'” Surely it can’t hurt that — having defied Lester Bangs’ famous advice — he has more rock-star friends than just about anybody in the business? “I don’t know if friendship can last into the wrong kind of musical theater usage,” he points out. I had a couple conversations with people where I was like, ‘Listen, I’m here every day. I have your same phobia about the wrong version of how to do this.’ There are songs that have been in and out. I was real happy that Joni said it was okay to use ‘River.’ It’s new for a lot of people, seeing some of their music used that way. But the funny thing is, a lot of them are trying to do their own plays too now, like a musical of ‘Rumours,’ and it’s all kind of flowing in that direction. So maybe we can show how you can love music and honor it and not get too glitzy about it all. It’s kind of a new way to watch music.”

The blend of a little Led Zep and a whole lotta original music works seamlessly enough for audiences, says Crowe, that “it’s surprising to me how few people know that ‘It Ain’t Easy’ is a David Bowie song. They’re like, ‘I like that song you guys wrote for the deflowering scene.’ It’s on ‘Ziggy Stardust,’ baby — come on!”

Crowe allows that the whole concept “is a little bit of a mashup, but it’s intimate and heartfelt. And even if it goes beyond the Old Globe, I don’t think it’s built for a cavernous theater, like ‘Wicked’ or something like that. It should always feel like the movie, where you can wrap your arms around it and call it your own.”

Crowe’s confident the moments of pathos that were part of the original film have survived the transition to a musical, even as some of the laughs inevitably get played broader on stage. “We all kind of wanted to get to the deep ache and happy/sad feeling that’s kind of at the heart of ‘Almost Famous.’ And I still am not sure why it’s connected as well as it has, because that’s all I hear about anymore, of the stuff I’ve done. At a certain point I stopped hearing about ‘Jerry Maguire’; it’s just ‘Almost Famous.’” Did ever thing about doing “Maguire” or “Say Anything,” say, as a stage musical, too? “No. Just this… It was always about the feeling that a great song or a great record, heard at the right time in your life, will sear you with. And if the show can kind of capture that thing that Faruza Balk says in the movie, about how you forget what it is to be a fan, to hear a piece of music or even see an album cover that means so much to you that it hurts, that’s still at the heart of ‘Almost Famous.’”

He pauses to think ahead, beyond Broadway, even. “From the very first time we talked about it, I was like, I would want a kid to want to direct ‘Almost Famous’ the musical for his high school. I want it to be something that’s tight enough that somebody would do it as a high school production. That’s the dream. It can’t always be ‘Grease.’”

Crowe isn’t just thinking about himself and his show. “I want somebody to do ‘Springsteen on Broadway’ as a high school production,” he declares. “I just think that would be the greatest. A 16-year-old kid as Bruce? It could happen. Or a girl! It could be amazing.”

Kitt relished the chance to work with Crowe on the songs for the production. With the director providing a fresh eye as someone who had never done a musical before, Kitt is the yin to that yang as the guy who’s done just about everything that the show requires, in theory. On top of his award-winning musicals that were conjured up from scratch, he’s done the music for film-to-stage musical adaptations of “High Fidelity,” “Bring It On,” “Freaky Friday,” “Dave,” “Magic Mike” and “The Visitor.” (Some of these are still in their own transition to Broadway: “Dave” had a successful run in Washington, D.C., and “The Visitor” is having a production at the Public Theatre this spring.) As far as the so-called jukebox elements go, Kitt has also served as the arranger on the Green Day-based musical “American Idiot” and the soon-to-open “Jagged Little Pill,” with its score full of Alanis Morrisette songs.

Kitt’s timeline indicates just how quickly this came together, by Broadway or pre-Broadway standards. He’d first heard of Crowe’s interest in doing a show three or four years before their initial meeting in the summer of 2017, at which point everything gelled. “Cameron had a draft he was working on when I first came the project. That first initial collaborative writing period began in earnest around December of 2017 and culminated with handing in the first draft in April of ‘18. That five-month time period was quite prolific for both of us.”

Working on words with Crowe was worth waiting around a few years for that first meeting, Kitt says. “I think what Cameron does is, like any great writer, he makes poetry of things that you feel every day. We can all draw lines from his writing that we wish we could express ourselves that way, at the drop of a hat, that he seems to find language for. Writing the songs with him was exactly the same thing, where I just wanted to pick his brain and hear those thoughts and feel that language that only Cameron Crowe could come up with. There were all rich characters to get to write for, and the fact that they come from Cameron’s mind, that I could be there with him just sort of absorbing all his thoughts and with him channeling them into songs… I would often say to him. when there was a song we had to maybe look at adding, ‘It will never feel like work to write a song for “Almost Famous.” So yes, let’s just write another one.'”

Stepping into film-based roles that can legitimately be considered iconic 19 years on was something the cast had to think about… and then not think about. Says Solea Pfeiffer, who plays Penny Lane, “Kate Hudson played it to just such perfection, and I marveled at her performance in this movie from the moment I saw it, before I ever thought that I would be bringing it to the stage. The movie will always be there for the people who want to revisit it. And now this is ours, and it’s just about taking ownership of the things that made this character so iconic. I think there’s something about the reason Penny Lane resonates with people so much, and it’s more about the spirit than just one specific performance. Whenever I’m about to go on stage, it’s like imbuing yourself with such love of the people around you, and our experience as a cast with this show mirrors so much of what happens in this story, in terms of like finding your family and your people through music.” She did force herself to rewatch the film on the plane out to San Diego, despite telling herself she wouldn’t. “It used to bother me, but one big thing about Penny is confidence, and I feel like I’ve become so much confident just playing this — like, maybe you’ll love me! Maybe you won’t!”

Talking with Crowe, Pfeiffer says, “One of the coolest things was realizing that he had put himself into the Penny Lane character, just as much as he had into William in some ways. Penny is obviously an amalgamation of the real Penny herself and other women who are part of the story. But when she talks about going to the Rolling Stones concert when she’s 14 and rushing the stage and getting crushed, it’s clearly a monologue that I say in the show, but (one day) he was telling the story, and he went, ‘And I never went home'” (just like Penny does in the screenplay and musical). “I was like, oh my gosh, that’s it — you have put yourself into it. And why Cameron connected with this character so much is the way that she listens and is there, and so is he. I haven’t really met anyone like him, exactly, who you just want to tell him everything, and he makes you feel like everything you’re saying is so important.”

For Colin Donnell, who assumed the role of rocker Russell Hammond, he found himself basing his portrayal less on Billy Crudup’s than on the Eagles’ Glenn Frey… or at least the version of Frey that Crowe conveyed to him.

“He and I have talked about the relationship that he had with Glenn a lot, and I watched the ‘History of the Eagles’ documentary, and there’s something inherent about the relationship that Cameron and Glenn had that is totally suffused throughout our show, and especially the relationship that William and Russell have — the older brother attitude, the guy who was magnetic enough to walk into a room and automatically give somebody a nickname, no matter if they’d met for the first time or it was the 20th time that they were seeing each other. So I think there is a huge amount of Glenn in there.” It didn’t hurt, Donnell says, that, even though he’s still a youthful 36, “the first song I ever learned how to play on a guitar was ‘Take it Easy’ by the Eagles.”

Donnell is probably the most famous (we can leave out the “almost,” right?) member of the cast, having been on prime-time TV for multiple seasons of “Arrow” and, most recently, “Chicago Med,” from which he was recently cut loose after four seasons. That amicable severance premiere) “was just a really serendipitous deal” when it came to being able to settle into a hoped-for long run with “Almost Famous,” he says. “I’ve been working on various workshops and readings of the show since they put the whole thing together; about a year and a half ago did this two-day little deal inside of a room in downtown New York and there wasn’t any music, just lyric sheets, and I don’t think any of us actors knew where in the process they were. But I knew that I loved it, I’ve always loved the movie, and I’ve always loved trying to keep my toes dipped in the water of what’s happening in the New York theater scene. And I was just feeling like I would really regret it if I wasn’t able to be a part of it. Of course, I had obligations elsewhere and it’s not like I was going to try to shirk those to come up over here, but the universe aligned for me.”

There was also some serious alignment going on when the show’s lead actor dropped out July 3, only two and a half months before the show’s two weeks of previews at the Old Globe. Their new find, Casey Likes, “was a runner-up at the Jimmy Awards, a guy from Arizona, and the only thing you could find online was him singing a Bruno Mars song and giving a girl a flower in a bleachers moment somewhere,” says Crowe. “But he’s the guy. And he’s the right age, 17. The other guy was older and more skilled and kind of had some Broadway experience, bit Casey is not unlike Patrick Fugit in the in the original movie. He’s stepped into being this leading man, and he’s just a kid from Arizona..”

On this opening night, when he should be all nerves, Crowe seems at peace, maybe in part because he nailed one particular character moment right before the script went into lockdown, following a line that’s familiar from the original screenplay with a comeback that cements just how much the show is about using music to find friends or just overcome loneliness.

“Casey is getting really adept at the character and comedy and stuff. And you never get to do this, really, in film, where you can come up with an idea in the afternoon and that night it’s in front of an audience. I mean, it’s like a stand-up comedian or something, where you get immediate gratification. But there’s a conversation he and Penny Lane have, where I want them to be friends away from the glamour and the spectacle of rock, like they find each other kind of as the real versions of themselves. Penny Lane says, ‘I need a new crowd’ And I thought it’d be great if he said: ‘I need a crowd.’ And he nailed it. It was just like, whoa — that’s fun.”

One important question: Lester Bangs, the real-life rock critic who gave Crowe his start and who figures into the movie and musical as a conscience, is the one major character who doesn’t get a musical number. Was Crowe afraid that Bangs’ angry ghost would come back and disrupt the show, if that happened?

“This is the greatest question of all time,” Crowe says. “Yes is the answer to that question. I felt he would arrive and stop it if he sang.”

Nonetheless, between the first weekend of previews and opening night, the production added a curtain-call bow number in which Rob Colette, who plays Bangs and is a very capable singer, does finally get to wail a couple of lines. This is a show that seems to be so charmed this far in its development that it can even risk a haunting.