I have a 1968 plate on my Barracuda. Tomorrow is the one year anniversary of Ohio not requiring a front plate.
25 years or older qualifies for Historical plates that are black on white. You must get historical plate registration first and take your YOM plate to DMV for approval. Must be legible and not rusted out. Little known fact is that it is ok to paint them to match your car. You are supposed to carry one of the historical plates in the car at all times but does not have to be visible. There is a one time charge of about $40 for Historical plates and they are good for 50 years with no annual renewal. Restrictions are that vehicle cannot be used for general transportation. I keep a Cruising Times magazine in the car in case i get hassled because they list the daily cruise-ins so I can say I'm on the way to a show.
I have regular plates on my 64 as I drive it a lot but I'm thinking I'll go to YOM plate on that one too.
One of the CA guys mentioned that he didn't understand why all states don't just keep the same plate for the life of the car. The answer is RUST!
Ohio switched to one plate with renewal stickers about 1973 and went to aluminum. About every 5 years they come out with a new design and there are about 4 current colors out there. But they announced recently that the oldest won't be renewable this year.