67 dart rear end modification

Power wise, you’re going to be right on the verge of what an 8-3/4 can tolerate. You should really run a back brace on the housing at this level. It’s been a while since I’ve seen what your looking at with the tire size after the three inch relocation, but @Oldmanmopar would probably be able to tell you. A stock width axle might be possible with enough positive wheel offset (a LOT of backspace). Great Looking Build!