Spring offset and rim and tire size 68 Barracuda for thos who have done it

I'm thinking of moving my SS springs in with the 3/4 offset spring relocation kit. Don't want to mini tub. Right now I'm running BFG 255/60 15's on 8" rims with 4.25 backspace.
Input on what combination tire and rim backspace you guys who have done it to a 67-69 barracuda are running would help a bunch in my final decision.