I am told that none of the older stuff will work. 502 heads will work. Cranks are all cast, and use one piece seal type flywheel.
I accidently acquired one for the shop this spring from a local truck repair shop for $75.00 (core engine). They thought it was a 502, as it uses all the same external parts. This one had a noise, that turned out to be a spun rod. The rods are longer than a stock big block. I believe they were +.400 stock. We ground the crank and resized the rod. Freshened the rings and bearings and sold it to some very lucky person on Ebay. I would have liked to keep it..