I believe this has information on specially constructed as well as kit cars but it's been a while since I've used it.
https://www.semasan.com/resources/everything-you-need-register-and-title-your-hobby-car-all-50-states
I will say your experience will vary based on who you get at the counter at the DMV and who you can get on the line. My Exocet I talked with the main guy at the state and we registered it as a Lotus7 replica instead of a kit car because in Tennessee it was easier, but that wasn't what they said on their website/info - so like Keith said, best to go and talk to some people. Also worth going on the locost forum to see if anyone has registered in your state. Worst/last resort is using the title/plate of the donor vehicle, but of course that's not ... Exactly the best idea depending on your insurance, police, etc...
