Rear wheel and tire combo ???

I've got a 1970 dodge dart with a 7 1/4 rear end. I recently converted the front to disc brakes brining it to a 4 1/2" bolt pattern. The rear is still a 4" small bolt pattern. I need help with the rear wheel and tire combo I am switching to 15" wheels to clear the front disc brake set up. What can or should I run for a 15 inch rim, width? And offset?band what tires will fit without any modifications?

The front I ordered 15" diameter 6" wide with 3.75" of back spacing. Is this correct as well?