For years it has been whispered in artistic circles. Now it’s official. Al Pacino will play King Lear on the big screen, heading the cast of a major film adaptation of Shakespeare’s tragedy that starts shooting next year.

Pacino made his name playing gangsters and cops in films such as The Godfather, Scarface and Serpico. With King Lear he is following in the footsteps of Laurence Olivier and Orson Welles, and taking on one of the world’s most coveted acting roles.

The story of a once-great monarch’s descent into madness will be directed by Britain’s Michael Radford, whose films include Il Postino, for which he received an Oscar nomination.

Pacino, 78, and Radford are reuniting with producer Barry Navidi following their critically acclaimed The Merchant of Venice, the visually sumptuous 2004 film in which Pacino played Shylock. Describing the role as “humongous”, Radford told the Observer: “Lear is the one that everyone aims for. Al has been toying with the idea for a long time. There’s a difference between Shylock, who’s only in five scenes, and Lear, who is in every scene, pretty much. It’s enormous. I think [Pacino] would like to have that kind of kudos because he’s a terrific actor.”

Revered for his intense acting style, the American star began his career in the theatre, making his name after Francis Ford Coppola cast him as Michael Corleone, the gangster’s son, in The Godfather. His acclaimed documentary Looking for Richard reflected his lifelong passion for Shakespeare.

Pacino’s portrayal of Shylock in The Merchant of Venice was applauded by the critics. Philip French in the Observer praised Pacino’s “complex portrayal”, describing the movie as “handsome”.

It also did very well financially, points out Navidi. “The theatrical box-office, together with DVD, was close to $32m, which is pretty good considering most Shakespeare films gross between $10m to $25m.”

Pacino has said that Shakespeare on film “should be tried more often… to take the humanity that Shakespeare writes into characters and express it”.

The shoot is planned for next autumn. Navidi said: “Before, we had the passion and the desire, but we never had a start date. We all have the energy to do [King Lear] now. We’re creating, hopefully, an epic.”

He described the adaptation as “very faithful” to Shakespeare. “Michael and Al are going to stick to the original poetry,” he said. “But a lot is to do with the delivery and the visuals. How Michael combines it and makes it more accessible, it becomes naturalistic rather than forced.”

As a British production, it will be shot in the UK. “The thing about King Lear is that it’s not set in any particular era,” said Radford. “It’s a fantasised era where there’s some place called Dover. I’ve been talking to a big special-effects company, thinking ‘what can we do to create something that doesn’t really exist?”

“A lot of people think of Lear classically as being in some sort of medieval world where people wear rough-hewn clothes. I want the world to be recognisable – not recognisable physically, but psychologically.”