Having wrapped on his Transformers trilogy (although who knows if he'll be lured back), director Michael Bay has turned his focus to the dark comedy Pain and Gain.  The story is based on a 1999 Miami New Times article about two bodybuilders who got caught up in an extortion ring and a kidnapping scheme that went terribly wrong.  In October, Bay said of the film, "It’s a very quick shoot and quite funny."  Pain and Gain has been one of Bay's passion projects for the past decade and carries a reported budget of only $20 million (the word "only" is used because of Bay; few other directors would get that adjective in front of their budget).According to Variety, Dwayne Johnson and Mark Wahlberg are circling the lead roles, although their participation will depend on scheduling.  Hit the jump for more. [We've updated the story after the jump]Variety reports that the production is still in the early casting stages, but Johnson's participation is further along than Wahlberg's.  Wahlberg's more of a toss-up since he'll have to find time in his busy schedule in order to join the project.  He's currently shooting on the crime-thriller Broken City and he's considering whether to make the action flick 2 Guns or the Adam McKay comedy Three Mississippi afterwards.  As for Johnson, he's about to start shooting on the action-thriller Snitch before moving on to the sixth and seventh installments in the Fast and Furious franchise, which Universal would like to shoot back-to-back. [Updated: Variety's Jeff Snieder has tweeted: "UPDATE: In the 3 hours since we published our PAIN & GAIN story, MARK WAHLBERG has officially passed on the project... @TheRock's still a go."]Captain America screenwriters Christopher Markus and Stephen McFeely wrote the original script and per Variety, "have compared its tone to the Coen brothers' Fargo which was also based on a true crime story."  Film nerdery: Fargo wasn't based on a true story.  The Coens put that in front of the movie to help suspend the audience's disbelief.  It worked.