Resurrection Fighting Alliance veteran Jason Gonzalez will make his Octagon debut next month at UFC 203 , according to an RFA official.Gonzalez, who has won six straight bouts – all by either knockout or submission – will replace Erik Koch , who had to withdraw from his bout against Drew Dober . Gonzalez’s bout against Dober will take place during the Fox Sports 1-televised prelims.The Las Vegas-based promotion has yet to announce the change for UFC 203, which goes down Sept. 10 at Quicken Loans Arena in Cleveland.UFC 203 will be headlined by reigning heavyweight champion Stipe Miocic defending his title for the first time against former K-1 World Grand Prix champion Alistair Overeem