We have the grey/green paint for the block and head but what about the accessories? Oil pan, water pump, side valve cover, timing cover, oil fil, harmonic balancer, etc. What color were these? Thanks!

My car had an engine overhaul prior to my ownership, so it's possible some stuff got changed up. In any case, for my car ('38 40 series)
Oil pan: Mine is bare metal
water pump: mine is black/slight gloss
side valve cover: mine is engine color green
timing cover: mine is engine color green
oil fill: you mean the cap itself? mine is bare metal
Starter and generator are both black/slight gloss on my car.

I would think that all those items in your list should be engine color. Buick painted the engines after assembly but before accessories were installed. Some people like the highly detailed look of exposed gaskets that aren't painted and bolt heads that are either painted after assembly or left plated, but others like the original look of everything sprayed at once. There's probably no difference in judging either way.

Hope this helps.

For a real eye opener as to how engines were actually painted at the factory talk to Joe Vicinni about his years with Chevy, including '57 I think. I attended his seminar. He says the engines were painted with carb and manifolds attached with only a piece of cardboard held in the painter's left hand used to mask the crab, manifolds etc.