1968 Dodge Dart GT Sleeping Beauty?

The 7 1/4" rear absorbs less power parasitically than larger (8 1/4" or 8 3/4") offerings. To maximize power, the smallest axle housing that can handle the job is the best one for the job. I think you already know this, though.
You give me too much credit. I was doing the 7 1/4 based on $. I knew it was strong enough for my use.