At what point to go Dana 60 ??????

1) Don't cut an oem A-body housing and 2) go ahead with the Dana 60. If you're narrowing a rear, now is the time.
It’s not an original A body rear. It started life as a C body rear that I turned into an A body rear. I did this 5 or 6 years ago. With the 2 1/2” breaks I had to roll the fender lips just to keep the 245 60 tires from rubbing. Now I am getting ready for a redo and trying to figure out which direction to go. I have a couple spare 8 3/4’s so I probably won’t cut the stock width one in the car if I go that route.