Sometime in the early 1970's grandpa replaced the original drive train. I think some of the parts came out of a junked out station wagon, most likely the 55 - 64 Chevy rear end and drive shaft. A stong TH400 with a shift kit was put behind a 396 Big Block. My uncle remembers the engine being bored .30 out at Keith Black's shop. Grandpa also built the headers from scratch. That's about all I know, we haven't talked much shop beyond that, and the torn down shot is the only picture I have of the original engine.
The wheels are early 70's Centerlines, bought brand new by Grandpa for the panel.
The glamour shot is basically how the panel remained through out the late 70's and 80's. The bubble windows and rearviews were both swap meet finds. Very groovy.