So how should they be finished. They look like they might have been plated, but there's only specs of bronze on them.

I believe they were cad plated, but I just used a wire brush (on a dremel) to clean them up and then painted them gloss black...worked fine, unless you are looking for the concours restoration.

Clear/silver zinc. I don't think I've ever seen gold/yellow/cad ones.

I vote for same finish as the intake runners
Click to view attachment

2 tone them the same color as the car...Click to view attachment

like this

and this