I was big into novas before I got into chevelles and camaros, and here is some info I got hands on, not just article stuff.
8.5s came in some 72 novas, and were in novas straight up to 79. 73-74 nova rears will bolt in a 67-69 camaro, 75 and later rears will not. In 75 the platform changed to share the suspension of the 70-81 camaro. If you want to put a 75 and up nova rear in a 67-69 camaro you have to move the spring perches. The rear will also be 1/2" wider on each end, but it will fit. Same deal if its a 70-81 camaro rear, but again 8.5s didnt show up until 72. Cheapest way to go is find a mid 70s z28 rear, most were 3:73s and are way less money than a 12 bolt. Move the perches and youre set, just did this with a 69 camaro a few years ago.
66/70 chevelle ss396's