Rear end swap to an 8 3/4

I need a new rear end for my dart. A 400 ish HP 360 is going in and I know for a fact my 7 1/4 won't be very happy if I keep it. It's really only a street car so I figure an 8 1/4 or an 8 3/4 would work well. My dart has factory front disc brakes and the big bolt pattern. What rear should I look for that would fit with minor modifications? And is there any way I could modify the new rear to accommodate wider tires without tubbing it?