315/60R15 vs 295/50R15 Rear End Length for Dart Sport

I'm currently working on the measurements for the rear end for my 73 Dart Sport and would like some opinions on the following. The car is mini tubbed with the springs moved to the rails. I already have MT 315/60R15's mounted on Cragar SS rims. The problem is that the wheel diameter is to great (30") to fit up into the fender wells without hitting the front and rear of the fender. I could run these but the back of the car will probably sit higher than I would like. Right now I have a inside rim to inside rim measurement of 52" (anyone know if this sounds reasonable?). If I want to get the wheels up into the fender wells it looks like I will need to go to a 295/50R15 tire. What I'm trying to figure out is if the 52" measurement will be good if I use either the 295 or the 315. I think it would be fine but I'm trying to make sure I don't miss something before I order the rear end. Thanks!