Not worth your time IMO to do the swap. The pinion size and spline is almost the same small size as the stock 7.5. I have one of those same rear ends laying in my backyard that I can't give away! I bought it thinking it was an 8.5' and suprise, I was wrong! Don't know where you are located but down here good 12-bolt Chevelle housings can be had for around $300, but once you buy a good posi unit and ring and pinion gears, axles, etc... You are looking at lots of $$$. I bought a built 12-bolt from a friend for my car, but homestly if you are going to have to build a rearend from scratch, Go with a 9". If you look you can find a new bolt in housing for less than $400, and you can buy used stuff cheap all over the place. Only thing you would prob have to buy new would be axles. And a 9" is prob a lot stronger than the the 12-bolt too. I know someone near hear with a full race '72 Chevelle 8.5" 410-bolt with good axles, spool, pro gear(4:88), Cclip eleim, and Aerospace brakes with very few runs for about $800.
