There aren’t many peppy musicals charting a gay composer’s brain tumor diagnosis and mysterious recovery. A revival of this sometimes glib 1998 offering by songwriter William Finn and playwright James Lapine continues Porchlight Music Theatre Chicagos “Finn Festival.” Partly autobiographical, the work artfully omits one fact: Finn was misdiagnosed with a tumor. If he’d been honest about his situation, these 90 minutes might have been more about anger than relief. Unflaggingly delivered by L. Walter Stearns’s cast, rousers like “Heart and Music” drive home the mellow message: if not mind over body, then art over science. Still, there’s no shortage of muddled moments, as when Finn’s surrogate (Stephen Rader) blames a homeless woman for snagging the books his mother threw out, believing they somehow caused her son’s illness. A New Brain contains dark moments despite the protagonist’s escape, but Finn’s suspiciously sweet score ignores these. Through 5/22: schedule follows. 5/7-5/8: Sat 8 PM, Sun 2 PM. Then 5/13-5/14: Fri 8 PM, Sat 2 PM. Then 5/21-5/22: Sat 8 PM, Sun 2 PM. Theatre Building Chicago, 1225 W. Belmont, 773-327-5252. $27-$30.