So what happens if you keep the old /6 rear end after 360 swap?

I even put a shift kit in the 727 while the 7 1/4 was still in there.. guess I will thank the mopar gods for the fluke rear end... my 8 3/4 has a 742 case with 323's ... that should be plenty for all I intend to do with the car.. I really only want a cruiser for my honey and I, but when Im at a light, if I want to smoke the tires off a little I shouldnt have to worry as much as I did with the 7 1/4 LOL ...