Some states (thanks to SEMA) have passed legislation that allow kit-replica-etc to be registered as the year of the vehicle they replicate. The advantage of this is mostly in the hassle that it saves and a little money. For me it meant I could get year of manufacture plates. 1966 plates, no emissions test, no front plate required, no mileage limits. As to the value for overseas sale. Some will accept the title as proof of age while others (Norway and Australia for example) don't care what the title says, but require proof of date of manufacture. Such as a title or registration (government documents) that have a date that shows required age of vehicle. 30 years old in most cases. So if you intend to sell overseas the dollar value can be significant.
Just went through all of this with the sale of my car.