Len Cariou, the actor best known along the Rialto for his perf in the title role of the original production of “Sweeney Todd,” will direct a new tuner, “Rob Roy The Musical,” in Chicago in the spring.Show, about the 18th century Scottish hero Rob Roy MacGregor, has music, lyrics and book by David Warrack, the founding musical director of Canada Pops Orchestra. Tuner preemed at the Edinburgh Fringe Fest in 2006. Show stars George Masswohl in the title role, with Susan Gilmour as Rob Roy’s wife. Produced by Warrack and Bernard Abrams, show is exec produced by Bernadine and Hugh Cameron with Mitchell Schmiedling as associate producer. Production plays Chicago’s Arie Crown Theater Feb. 3-March 15.