The Broadway-bound "Purple Rain" has landed a pair of heavyweight backers — and with them, great expectations. "Hamilton" creator Lin-Manuel Miranda and his father, Luis Miranda Jr., have signed on as co-producers of the stage adaptation of Prince's 1984 film. For "Rain," the lead producer is Orin Wolf, who oversees hiring, firing and major decisions shaping the production. According to industry insiders, "Rain" has stirred a powerful emotional response among Broadway backers, much as it did before its world premiere last October at Minneapolis' State Theatre. "Prince gave the world one of the greatest albums ever made, and now that story takes the stage," the elder Miranda wrote.