[38 coupe]

The aluminum intake was left natural.

If you are duplicating how Ford painted the engine then you have a bit of masking work to do. Ford painted the cast iron parts, then machined them, then assembled them. All machined surfaces on the block, heads, and timing cover should be bare metal. The head studs are bare metal. The head nuts are cadmium plated (I think) and are not painted. I clear coated the bare surfaces on the last one I painted like this.