Yeah, agreed - spring rate would need to be spec'd, and the narrower spring would arguably work harder, it was just a thought for a cheap way to gain clearance.
It avoids modifying the rear axle perches.
Many times, 1/2" makes all the difference...and yes, I realize that's a set-up line for a wisecrack, which I would reply with myself

Dr Diff has a 1/2" kit, but I'd assume re-drilling is required for the axle's spring perches.
I've previously found that the MP 3/4" kit doesn't really do much, but A-bodies are always dimensionally "casual" around the rear wheel openings.
All of mine have been tighter on the right than the left, from 1970 to 1974 so far.
Of course, the real cure is the "nuclear option" of the 2" deal, cutting the rails, welding in front boxes, and "while you're there", mini-tubs & narrowing the rear axle.
But that's beyond the budget/time/whatever for a lot of folks.