To paint the cap is one way to do it but when I checked out the cap it has chrome on the inside. I'm not sure how well the fuel caps were painted back in the days. If I paint the front side of the cap it will be chrome on the backside. And I'm not sure it could be correct to disassemble the cap before painting it and then weld the thing back together!
The best way would be to found an assembly line cap and then have it painted. But those assembly line stuff don't grow on trees....!
The wiring system under hood is done and complete now. Al the stuff is there incl all the small part number tags. I added the heater hose clamps too so now it looks the way it did back in early 65.