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

I'm learning as I go so this is where things are now. I began this by trying to go with the greatest diameter wheel I could find that was in the 315 range and would fit on a 15" rim. It just never occurred to me that the wheel wouldn't fit all the way up in the fender well. The distance between the front and back of the fender is about 30 1/4" and the tire is 30"+-. Then for some reason I got it in my head that there were no tires in the 315+ width that would fit in a 15" rim with an aspect ratio less than 60. Well I was laying in bed and thought wait a minute why did I think that. I ended up getting out of bed and pulled up some tire specs. This is what I found available:

BF Goodrich P295/50R15 Diameter 26.6"
Mickey Thompson P295/55R15 Diameter 27.8"
Mickey Thompson P325/50R15 Diameter 28"

It looks like any of these will work so I'm going to go with the MT P325/50R15. Concerning the rear end here is what I have figured out.

1973 Dodge Dart Sport
Mini-tubbed
Springs mounts moved to the rails (although I'm going with a 4-link)
Cragar SS Rims 15" x 10" with 4.5" Back Space

Inside Rim to Inside Rim 51-1/2"
Housing Width 46"
Spring Perches 36" On Center
Axle Flange to Axle Flange 51"
Disk Brake Width 1/4" Each

This rear end width should let me run any of the tires above. I ordered the rear end from Dr. Diff, a Strange S60, and if I remember I'll post when this is installed and let you know how it worked out.