CAN THE PINION ANGLE CHANGE ?

So, the Dana wasn't original to the car it was in, and the 8 3/4 wasn't original to the car it was in, and someone else did all that work before you got them.

So really, you have no way of knowing if either of those rear axles are originally B-body axles, or if the perch angles are the same on both axles, or if the perch angles on either rear axle were correct for a B-body to begin with.

That's before we address different springs, ride heights, driveshaft lengths, etc.