Need some purchasing advice

You left out a lot of info on that car that could help us advise you. It's been converted to big bolt pattern wheels with disc brakes in the front and it SAYS an 8 3/4 with a 489 sure grip with 3.91 gears. I'd find out HOW that was converted to the big bolt pattern, as the A body 8 3/4 never came with the big bolt pattern. A few ways to do it, so it's entirely possible. Hard to tell without seeing it in person. Have you inspected it yet? Car's on Marketplace in the Dalton area. It might be worth it, but as usual, an astute buyer will want to get it at as good a deal as possible. Looks pretty good from all the pictures, though.

EDIT! My bad. All your text didn't show up for me at first. I see you did include all that info. It's worth going to look at.