Most 1935 and 1936 car engines came with aluminum heads and valve cover (intake manifold) and the aluminum were left unpainted. In general, machined surfaces on the block are unpainted. If you want this look, I suggest using a clear coat so rust doesn't come too quickly to these surfaces.
The block is Ford Green and I think Hirsch has the best paint for this application. If using cast iron heads or cast iron valve cover (like for a truck), these should be painted the same engine green. Pan is gloss black and water pumps are engine green too.
There's a lot more detail such as the finish on the fasteners to be concerned with if you are going for a show car or are particular about it, but that's entirely up to what you want to do.