First welcome to the site - how you find it helpful in your concours related needs
You will find out quickly that we will ask for as much information as possible in an effort to provide the best information we can. You might consider entering your cars information (when, where it was built, and how it was equipped) as your signature or your going to be typing it over and over each time you post a request.
For this question you don't give us any idea of what transmission (three or four speed) what size engine and so on. So the generic answers are
Clutch fork - natural bare steel
Bell housing - bare with engine paint overspray from painting the engine with the bell housing attached
Transmission- Bare cast iron look to the main body with machined surfaces that would contrast. Nice new stamped steel cover. Cover and tail shaft housing to main case bolts - phosphate or darkened heat treated
Linkage - depends on what transmission you have and the other details.