I've run these cars for 30 years. If I can buy a fairly bullet proof piece for a reasonable price I just don't know why I would spend almost the same price on a piece I would be wondering about. A dana is one of the best values for $$$ out there. You have a 4 speed, fairly heavy B-body with somewhat sticky tires. Do you really want to pump $500 or maybe $1000 into that 8 3/4 and wonder if it will last when you can put a new Dana in for $2k and be done with it?
Your car makes enough power to hurt that little 8 3/4 so you'll have to spend money upgrading it anyway.
Smallblock automatic in an A-body would be a different story.

Sheldon