tom68cst, check out the VCAA
Judging Manual . It details everything the judges look for in stock vehicles. Engine paint is not that critical in the judging as long as it is the correct color. They place more importance on the "correct" parts being used like, hoses, belts, hose clamps, batteries, spark plug wires, radiator, etc. If your's is already number-matched, then that's a big part of the battle.
I would paint the engine after assembly. Even if you paint some parts before assembly, they will likely get scratched, or messed up with gasket sealant, etc. Plus, it's much easier to keep paint off of the head and block surfaces if the enging is assembled. To
paint my engine , I installed the heads, valve covers, timing chain cover, oil pan, and intake manifold. I then masked those areas where I didn't want paint (crank shaft, manifold and carburetor ports, etc.).
I painted everthing else that attaches to the engine individually, then attached them before installing the engine. Worked for me.
I know that some engine compartment items on
Maych are not correct, but I thought I would enter him in some shows and let the judges tell me what items need attention.
Good luck with your 68. Glad you're going stock. Like you said, not many of us with this vintage are going that direction.