68 DART MINI TUBBED

I purchased a 68 Dart that has been mini tubbed and the springs moved in line with the frame rail. They used a 7 1/4 rear and added the new perches. I have a 8 3/4 from a B-Body that was under a 76 R/T ASPEN. I know the reference points for moving the perches on a B-Body rear installed in an A-body if the car has not been mini tubbed. Does anyone have any measurements that would get the b-body rear centered with the appropriate side to side clearance.