I have a fat boy in excellent mechanical condition, but the numbers and the black ring need restoration. It's a D4 and has the combination of nickel and black below the dial collar (see photo). I know how to repaint the numbers, but I am not sure how to paint the ring and leave the nickel part clean. I don't intend to polish the razor, as the finish is intact and authentic. I just want to repaint the numbers and the ring.