275/60/15 sidewall clearance to leaf spring clamps- suggestions?

Oops, That's why pretty much everyone on the planet runs 255's. I doubt very much if very many of us could tell you are running 275's. Not up close and damn sure not while you are driving by at 25. Sorry, No quick fix.

Actually a lot of people run 275’s on Dusters/Demons/Dart Sports. With the right backspacing they work fine on most cars in those bodystyles.

Problem here is the 4.5” backspace is what you need for an A-body 8 3/4 with BBP axles, which is too much backspace for the narrower 8.25”
I just looked up the dr diff not bad for the price seems easy to do- thought maybe you had to reweld to kick them in but the kit seems like straight bolt in

The hangers and shackles bolt on. The leaf spring perches have to be cut off and new ones welded onto the axle housing at 42” c-c (stock is 43”).