8 1/4 or 8 3/4 rear end

I have an unknown year what I believe to be B body 8-3/4 on a 72 dart. The factory wheels and tires clear with plenty of room to spare. If you want to go with an 8-3/4 I would measure what you have and get good measurement from Projectile Dart, it may fit without narrowing.

I wondered if it would fit being the the width in the rear is smaller than the front wheels and it looks like there is room to spare. Once i noticed this it makes the rear of the car look small.