if your going to use it commercially then your going to have to bite the bullet and pay the price. if you choose to go the other way then you chance losing your historic plates if your caught hauling with it which im sure there is also a cost with that too.
you need to ask yourself this, do i want an antique dump truck that i can haul with or do i want a dump truck that i can take to antique truck shows/parades?
i have a 51 2 ton that i chose to make a dump truck that i take to truck shows. there is a big difference in what it costs me vs how much i use the truck but i still chose the more expensive option.