for clarity..
we are talking rear leaf springs on an a body.
the front mount hardware/spring eye location on the front of the rear springs that mount to the chassis.?
if i recall only one of the studs/bolts (4 mounting studs total)is offset so you dont confuse them side to side..
I recall swapping them from side to side and flipping them over..then just drilling a hole in the chassis for that one offset stud..
this effectively raises the mount hole or lowers the rear ride height at the front spring eye mount..a small amount..
ive also seen guys..just drill out the spring eye bolt up or down ..depending on what direction you want to go.
this by the way moves the I/C fwiw..
cheapst