In every state I've been in, the title is to the VIN. I've use the frame VIN for titleing many vehicles. In this case, all you want is a good frame. The rest of the parts can come from anywhere.

If you want something really cool, have the frame galvinized. Just be sure that your suspension is setup the way you want it before it's dipped. You don't want to have to grind it off and reweld after it's dipped.

Next best, IMHO, UV protected POR-15. It's tough stuff, too. For the hollow sections, tie string or wire to a large shop rag, dip it in the paint, then pull the string through the tube. Do it a few times, and you'll get a good coat inside the box. I like Hammerite, too. It's pretty tough.

While you have the body off, put undercoating on it. I have used Kool Patch, by Koolseal, with GREAT results. I will not use any other thing for undercoating. Just don't mess with brushes, rollers, or nothing. You'll want to use disposable gloves, as it's like thick pudding.

Hope this helps