Relocating them inward would require a slightly shorter shock, not enough to mean anything. If you rearch the springs though, that could require a longer shock. After you do the work I would let the rearend droop on the springs and measure your shock free length to see what you need.
I used to see lots of upper shock mounts ripped out of 4 speed cars even with stock rear suspension. It was from powershifting and dropping the clutch but it shows what can happen with shocks that are too short.
Sheldon
, but OP forget KYB's