centering rear end

If I were going to move the perches, I would get a 1/2" offset hanger/shackle kit from Dr. Diff. You're doing all the work anyway, might as well get some extra clearance.

But, before I did that I would make sure that it was actually the perches that are off. Measure the distance from the quarters to the frame, and the quarters to the inner wheel tub and make sure it's the same side to side. No point moving the perches if the wheel tub isn't the same size.

Also, how do the leaf springs themselves look? What do the hangers and shackles look like? 1/2" isn't unheard of, but 3/4" is more than most of them are off. I would want to check that nothing was bent or damaged before I did too much fixing.