I just spent over $1100 totally reconditioning an 8 3/4 sbp for my 70 Dart.
the COMPLETE used REAREND drum to drum cost $325
a used742 case sure grip w/ 3.91 richmond gears with a new yoke cost $250
Parts to rebuild entire rearend,all wear items replaced except ring / pinion $300... replaced all bearings,clutches, seals, brakes,wheel cyl's,,hardware.... found new drums for 40 bucks on craigslist
Labor to rebuild chunk and set lash $125
I consider that I got the rearend cheap and "stole" the chunk (I shopped and scrounged for a year and a half) and still have over a grand wrapped up in it when I was done. . If I hadn't gotten the rearend with u bolts, shock plates, brake line tee, backing plates, e brake cables, the right yoke, and all the other bits, I would have been nickel and dimed to death before it was all over.
If I had to pay full price or close to it for everything, and scrounge for used bits, (for example shock plates $50, e brake cables $40 etc.)and buy a new ring/pinion, I could have easily spent close to $1800.
If I was doing it all over again and had the large bolt pattern, I would go with the 8.8. If youre in the situation I am with the small bolt pattern, its either get new axles AND 73 and up front disc set up to go to large pattern,(yes I know some have redrilled for large pattern but I would not trust that especially in a high horsepower situation) or stay sbp which SERIOUSLY limits tire selection.
you might be able to pick up the entire 8.8 rear for $200 or less and put that much or less in it to recondition it which would be 1/3 the price of an 8 3/4 rebuild. I heard a mustang motorhead say once that there were a lot of 3.73 gears put in the 8.8's.