Producer David Sonenberg has begun work on a legit musical version of “When We Were Kings,” the Oscar-winning 1996 doc about the Rumble in the Jungle, the 1974 boxing match in Zaire between George Foreman and Muhammad Ali.Score for the tuner will incorporate pre-existing songs from the era, many of which were featured in the movie, as well as some older tunes. The stage chronicle of the famous bout, during which underdog Ali famously bested reigning champ Foreman, will have a cast of characters that will include the well-known personnages who appeared in the doc such as Don King, James Brown, Norman Mailer, Mobutu Sese Seko and George Plimpton, plus the fighters themselves. “The story fuses music, sports, dance, politics, race and culture in a way that should appeal to a broad, pan-generational audience,” said Sonenberg, who produced the 1996 doc and has managed a pool of successful recording artists, including the Black Eyed Peas and John Legend, as the topper of DAS Communications. He also was one of the producers of 2002 Main Stem musical “Dance of the Vampires.” Songs by Brown, B.B. King, the Pointer Sisters and Bill Withers were among the tunes heard in the film. Additional songs will be selected for the legit incarnation by Sonenberg. The book for “Kings” will be adapted from the screenplay of the Leon Gast-helmed doc, which picked up the Oscar for documentary. Sonenberg aims to incorporate music into the story in ways that are more naturalistic than in traditional musical-theater fare, while still ensuring that “the songs are integrated into the emotion of the story,” he said. According to the producer, work has already begun on the adaptation, although he wouldn’t name the writer on board for the project. He plans to hold a reading of the show in Gotham later this year and is considering steering the musical toward an Off Broadway preem. Timeline would see the show open in 2014, or possibly sooner if things go well.