It's your cobrahead, you can paint it any color you want to. I'd personally leave the factory coat of paint on it because the factory coat is in good shape.
Bare fixtures aren't always shiney. They have to be polished if you want them shiney. And unfinished metal will corode faster. Painted looks better. It looks neater with paint. Bare fixtures just make me say "Eww". Just my opinion.
Well I have the same feeling towards painted fixtures, many lose their paint after a few years anyways and my painted FCO 125 has lost most of it's paint and is more corroded than any unpainted fixture I have ever seen.
The paint job was suckish then. Some lights from the 70's here still have their paint. The older T&B lights had better paint. All of the 13, 113, 25, and 125 from the 70's and 80's here have their origional paint.
Well I am debating painting this because The top housing is a bit.. beat up-ish and there are marks all over the top. Some on the bottom as well as you see here. But I still am not sure.