I have all pro springs on the back. They have really 3 runs on them ( a couple easy runs through the desert in Johnson valley with no crawling, just driving around, one trip down Cadillac and one trip up Cadillac from the round up this year) and a big bear gold mountain run. I added a leaf to them a couple days ago because the rear was sitting really low, about 3" lower than the front and I only had about 3" of shock shaft showing. That didnt change the shackle angle at all though . (I pulled the shock from the frame at the roundup). I'm getting bumpstops for it also. Would boomerang shackles help in the rear?
Btw, thanks for the compliment Mike. I'm also building an 82 short wheelbase pickup for my son and using ur thread as a guide. That 2nd gen runner you guys had at the marlin camp at this years roundup was awesome. Low ride and the 80 front axle was definitely an eye catcher. I'm guessing you know that guy, let him know I dig the build up.