Paul Weitz has recruited film thesps Topher Grace and Olivia Thirlby for the upcoming Off Broadway preem of his new play, “Lonely, I’m Not,” at Second Stage.Grace, making his legit debut, stars as a post-flameout business prodigy, while Thirlby is a businesswoman he meets as he begins to rebuild his life. Trip Cullman (“Bachelorette”) helms. Both thesps have previously worked with Weitz on bigscreen projects. Grace co-starred in the writer-helmer’s 2004 pic “In Good Company,” while Thirlby (“Juno”) — who appeared in the Off Broadway bow of “Farragut North” in 2008 — is among the cast in Weitz’s “Being Flynn,” the Focus Features release hitting theaters Friday. Weitz teamed with Second Stage on preems of his plays “Trust,” “Show People” and “Privilege.” He’s also worked with Cullman, who directed the scribe’s 2004 Off Broadway outing, “Roulette.” Further casting for “Lonely, I’m Not” remains to be locked in. Show begins previews April 10 ahead of a May 7 opening.