Joe,
You can be on the fence real easy with an 8.75" rear depending on power/weight.
I've built 8.75" rear ends that have lived in (2800 lb.) 10 second cars with trans-brakes. Then again I've had footbrake cars (heavier) spin the ring gear teeth off in 10 runs. To get it to live--back braced housing, steel caps, billet adjusters, etc etc, you can pretty much buy a pre-built Dana 60 less brakes.
Whenever one of my customer's breaks an 8.75" 9 times out of 10 they upgrade to a Dana 60.
My opinion, go Dana 60 now, and be done with it. You'll always want to make more power, and when you do, you won't have to worry about destroying that lil 8.75" ring gear.
Forgot to mention, when that 8 3/4 does break, it can severly damage the automatic trans (see exploding torqueflites thread at top). I just did one that had a stock VB, with shift kit (low band on in 1st). It spun the ring gear teeth off, rolled the sprag in the transmission, and broke the case! The next run it would have come through the floor! This was the gun-metal grey '72 Challenger that runs out at Bandi and Pueblo. Car goes 11 teens up here I believe, off the foot brake.
HTH's
