This has been a fscinating topic! I never realized there were that many General Motors truck kits available. I myself have the recent issue of the Chevy stepside, an original Blazer, and an original Jimmy. I just acquired an original GMC Sport Pickup from Ebay that hasn't arrived, yet. Would a rear differential from one Monogram's GM van kits be accurate for the rear ends in question, here?
We don't see many notchback Cudas in model building or 1:1. It's nice to see one that looks this good, and I'm talking about the model and the 1:1! (Have I made any sense?) I'll go sit down, now!
BTW: Great job on the wicked li'l blue Cuda!!
This is a very nice project! Ya gonna run a six banger in it? For the interior, I'd go with a similar color to the body, as a lot of cars that came out of the factory back then had interiors that closely matched the outside. Other than that, you might go with an off-white color!