Ohio is 25 years for Collector and 30 years for Historical. Historical plates never have to be renewed. That's how it was years ago anyway. I still have a car here in Arizona with Historical Ohio plates, they don't use stickers and are registered to the car for a life time according to Ohio. However AZ may not like that, lol.
Arizona is also 25 years and you can run a collector plate, which is called Antique I believe. I used to run them but they charge an extra $15 over the regular plates every renewal, and they don't provide any significance at all, so I stopped using them.
As far as registering those custom made plates, Ohio didn't care as long as the numbers/letters weren't being used. At the Columbus DMV they had a computer in the waiting room that you could run any sequence of numbers/letters for your county and see if it's been registered before you even ask about it. Pretty cool I thought. Dad ran the numbers, they weren't being used, so he had the plates made and brought them up there, they registered it no problem.