7 1/4 to 8 3/4 rear end swap. HELP!!!!!
I dont understand why you welded on new perches and you moved the springs.. wouldnt you just do one or the other?
If you do this, what I did when I moved mine was use a straight edge across the front of the pad right where it touches the axle tube, and I etched a line inward about an inch or so. If there is any weld spot there, grind it back gently so your straight edge butts up to the perch itself.
Then I cut the perches off very carefully, cleaned the area up and moved it in one half inch lining it up with that line I scribed and tacked it. Repeat on other side.
Check all of your measurements from axle flange to side of perch on both sides, making sure they are equal, then check center to center for the 43 inches.
The reason I did that was to keep the pinion angle the same. It worked for me. I checked it once in the car and it was perfect, no vibrations at all.
If you're on a tight budget, you CAN oblong the holes a bit on the shock mounts you have and use them until you can come up with the proper mounts. Just be sure there is enough meat left so they don't break.
You will need new U bolts, tightened to 45 FT LBS, with the weight of the car on the axle/springs.
Lastly, you will need to shorten your driveshaft and have it re-balanced.