Brake booster clean up questions

[77chevystepside]

I am needing some advice about cleaning up a brake booster. It is not painted-just original metal I guess
What is the best way to clean the oxidation off of the booster? I don't plan to paint it and wondering if it is necessary to spray it with clear coat after cleaning it or just leave it alone. I guess the same applies to the master cylinder cover. Just curious-was the master cylinder and booster painted from the factory? I am third owner so have no idea if this set up is original. I think I will paint the master cylinder black just to prevent the rusting that always happens. Other suggestions are certainly welcome.

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[VileZambonie]

You can't leave it unpainted or it will just rust. Even a clear coat it will rust. Use a gun metal grey paint if you want it to look natural. You can clean the rust off with a wire brush or wheel.