pinion angle

I think it would only be by shear luck if the pinion angles were the same. Since you have to weld the perches on anyway you may as well get an inexpensive angle finder (HF) and set the correct pinion angle after you get the leaf springs bolted to the axle tube. Then tack weld the spring pads, remove the rear end and finish welding the perches. Unless someone has detailed specs on the A & B pinion angles you'll never know for sure.

Treblig