72 demon rear wheels

looking at the 3" with 8 3/4 and stock wheel wells with 15" rims

Without a minitub the 3" relocation doesn't buy you any extra space. The 1/2" offset puts the springs even with the stock wheeltub. On my car the stock wheel tub is the limiting factor, not the springs.

You can do the 3" relocation, but you'll still be stuck with 295's unless you mini-tub it.