8 3/4 Questions

Thanks for all the info guys! The seller seems to know what he has, he told me that all a-body 8 3/4s have small bolt pattern. I don't mind the small bolt pattern. That is what I have now & I have the rally rims on it which I wanted. I am also looking at the scarebird disc brake conversion for the front so I could keep small bolt pattern all around. I am currently running what appears to be a stock '67-74 318 (not original) but plan on building a 273 or 360 to drop in. No more than 300-350 hp so anything other than the current 7 1/4 should be fine.
The guy with the 8 1/4 says it is also small bolt pattern. He also has b-body 8 3/4s for $200 but they would be the big bolt pattern & I would be looking for rims.
I am waiting to hear back about the casting # & sure grip or not on the a-body 8 3/4 so we will see how it pans out. All I need is a 9/16 socket, extension & ratchet to remove the axles & center unit? Is it obvious, I have never done it? Is it time consuming? Is the price too low, maybe something is wrong with it?

Thanks again guys, let me know if anyone ever needs any help.