Original License plate replacements?

Washington state lets you register a YOM plate to anything 25 years or older. The plate I got for my '69 was made up to '84 or so, so they are plentiful. You also only need one on the back, and no year or month sticker. They can also be restored, so I guess that means repainted the original colors. You can't use a repo. You also only need to register it once.

What if you get a personalized plate in CA? You can get them in yellow on blue, but what if you get one with the alpha numeric 6 digit pattern, and paint it yellow on black?