what size tire and backspacing

Hi, I have a 1967 Barracuda with the factory spring locations. I have a factory 8.75 rear with Yukon axles with 11" brakes and a 4 on 4.5 bolt pattern. The car has the factory tubs and 1/4's. Of course I want to run 15" wheels. Can someone please tell me what size tire will fit along with what backspacing is needed? Thank you