Some states (such as Florida) will not allow plates that have been repainted or restored. If you have plates (in Florida) that you want to use and they are a little rusty, (for the really old ones) scratched, chipped, etc., they must be used that way. A little rubbing compound, a good waxing, or bumping out some dents would be OK.
Nowadays in Florida if you have a vintage plate you want to use you must go to the DMV, get the proper form, and then send form AND plate to Tallahassee to get it approved, used to be the local DMV office could do it, but no longer. Been there. You can find license plate sellers on eBay that sell plates that have never been issued to a car, but of course you take what you can get. Check with your DMV if no one here can give you a definitive answer for NYS.