The Roundabout Theater Company has lined up a starry cast for a benefit concert reading of the 1963 tuner “She Loves Me,” with Josh Radnor, Jane Krakowski, Cheyenne Jackson, Kelli O’Hara and Victor Garber among the thesps on board.Reading will be helmed by Scott Ellis, who also directed the Roundabout’s revival of the show in 1993. The benefit event is timed to the 20th anniversary of the Gotham nonprofit’s Broadway producing activities, which kicked off at the now-defunct Criterion Center with a revival of Harold Pinter’s “The Homecoming.” O’Hara (“South Pacific,” “The Pajama Game”) and Radnor (“How I Met Your Mother”) will play two clerks at a perfume shop who hate each other at work but develop a romance as anonymous pen pals. Rory O’Malley (“The Book of Mormon”) and Michael McGrath also are among the cast. A 15-person orchestra provides the music for the concert reading. Tuner has music by Jerry Bock and lyrics by Sheldon Harnick, the duo behind “Fiddler on the Roof,” “Fiorello” and “The Apple Tree,” with a book by Joe Masteroff (“Cabaret”). Gala benefit will play Dec. 5 at the Stephen Sondheim Theater, one of the three Broadway venues owned by Roundabout, on a night when the theater’s current occupant, the Roundabout’s current revival of “Anything Goes,” is dark for the night.