For a green tag, you must prove ownership and provide a title and current registration. If it is a custom built vehicle, the CHP will do a full on inspection of the vehicle to assure it is what you say it is, as well as requiring all receipts from the build of the vehicle. Either way I see you getting in a bind pretty quick. Probably worse if they see grinder marks where the VIN used to be. Now if you happened to have a registered vehicle that needed a motor, maybe a buddy that needed a tranny and t-case, maybe another one that was interested in the body, then you could get some use of the truck. As long as no VINs are being run on this vehicle, the parts can go to good use.