[Joe Wicked]

If I was restoring the plates, I would sand blast them down completely and fill any spots that need it. Spray the whole plate with the color you are using for the letters first with whatever paint you are using (Rustoleum is what I would probably use). When dry, tape over the letters taking time to trim it properly and ensure you have a good stick. Then paint the rest of the plate the plate color. When dry, remove the tape and you have your plate. A very light wet sand on the edge of the plate color next to the letters will help remove any ridge or line.