You're right about Oliver using bronze (or was it brass?) brake pedals. The war had an effect on materials for years after it ended. Because of this, you'll find brass brake pedals and throttle quadrants, as well as aluminum hoods and side panels. Even before WWII, Oliver was doing this some, as I have seen pre-war 70s with brass pedals. 

I have also seen restored tractor where they did what you are suggesting, clear coating the brass parts. It makes for good conversation at the shows, and injects a little history while you're at it.