In Orange County near John Wayne Airport is a shop called Hillbank Motors.
www.MKIIIroller.com They sell the Superformance Rolling Chassis.
www.Superformance.com Everyone I have spoken with who has one is completely satisfied with the product. They look really sharp and well put together. They can provide many details about registering etc. Since the car is limited production it's obviously different than registering a mass produced car. Lot's of things you can do the the engine that can't be done with your typical assemnly line car. I believe Hillbank takes care of the DMV stuff.
Good Luck