Ran across this today. 340 4-speed with 440. Last registered 1982 $18K. Phone number is listed.
https://sfbay.craigslist.org/sfc/cto/d/la-habra-1970-challenger-speed/7050673105.html
Not an original CA car. I think the plate is mid 70's or so. Looks like it's missing the fender tag and the screws holding the dash tag on leave questions.
Neat car: Price seems high but you would have to fine tooth comb inspect the body. It looks like it needs a trunk floor anyway so price goes down from there.