I do believe that if you took an insurance claim for the theft, the car is not his, but rather the insurance companies. Isn’t that how it works?
Insurance was not compulsory then.
My '65 Mustang was stolen in '83 (I'd owned it since '79). Allstate paid me, IIRC, $2,500, a generous settlement at the time. If it were located, the insurance company is *supposed* to notify me and give me the chance to repurchase it from them. I'm sure that some cars end up recovered and auctioned without the previous owners' knowledge, though.
I recently found the old registration and VIN after years of thinking I'd discarded them. Yeah, I'm going to look into any subsequent registration of that VIN; you never can tell.