YOM (Year Of Manufacturer) Laws vary from state to state but one rule stands everywhere, the plate has to be form the year the vehicle is manufactured. I've had vehicles registered in various states utilizing YOM Laws (while in the military), some are 15, 20 or 25 years old and others won't allow it for anything newer than 1939 (VT) which forces you to place a new "historic plate" on your vehicle.
The other point to remember is YOU need to acquire the plates and in some areas those get expensive, make sure before you buy that the number is "free and clear" so you can actually use it.

As for Insurance, my two cents goes out to Geico's affiliate, American Modern Home & Classic Vehicle Insurance; I have a 1947 Willy's CJ2a, 1951 Willy's pick up, and a 1953 Dodge and the total is only about $150 a year for full replacement value of all three.