The various year corvette rears are different widths. I believe the 63-79 and 80-82 have a hub-hub width of around 57". I am using an 86 rear in a 52 chevy truck. (84-?? are 62.5 hub to hub but can be narrowed) Take a look at www.progressiveautomotive.com
I just ordered an entire chassis to fit my components under the truck. Bob, the owner of the ohio company is very clever, and has kits for almost any car.