Casting is coming together for a couple of summertime legit development programs, with Anika Noni Rose, Brian d’Arcy James and Gordon Clapp to appear in brewing stage works.Rose and James will topline a revised version of 1965 tuner “On a Clear Day You Can See Forever,” from helmer Michael Mayer (“American Idiot,” “Spring Awakening”). The musical getting a showcase as part of Powerhouse Theater, the developmental program from New York Stage and Film and Vassar College, where the seasonal session takes place. Peter Parnell penned the new book for the show, to be presented July 29-Aug. 1. Also at Powerhouse, Santino Fontana (“Brighton Beach Memoirs”) will star in “Bonfire Night” (July 16-18), a new musical by Justin Levine that’s directed by Alex Timbers (“Bloody Bloody Andrew Jackson”). Meanwhile, at Connecticut’s O’Neill Theater Center — which just picked up the 2010 Tony for regional theater — the ensemble tapped for the annual National Playwrights Conference includes Clapp (set to appear in Anne Washburn’s “A Devil at Noon”), Main Stem vet Barbara Walsh (in James McLindon’s “Comes a Faery”) and Off Broadway stalwart Reed Birney (in Molly Smith Metzler’s “Close Up Space”). Conference runs July 2-31. Laila Robbins, Mia Barron, Lynda Gravatt and Michael Chernus also are among the thesps lined up for the summer sesh, which will include a week of work on each of the slate’s seven shows. Each week is capped off with public readings of the plays being developed.