I had a similar deal on a '65 Coronet 500 daily I sold to a young guy, but it actually turned out kinda funny.
Started getting parking tickets on the car from various locations in L.A.a few weeks after selling it and advising DMV accordingly with the mail-in form.
I responded tot he tickets for awhile, even mailing in the new owner's info, but the tickets kept coming.
Eventually, the car was impounded by a tow outfit, and I received a notice of lein sale.
I knew a shop who did a lot of high-end stuff, and being L.A., he also did some commercial real estate in partnership with Sly Stallone.
At the time, he was doing a bulletproof Suburban for him.
Anyway, I go down, basically buy the car back for something like $350, and he tows it to the shop.
Stallone ended up buying the car from me, for his son, while it was sitting there.
And paid me more than the 1st guy, and more I had in it by a decent margin.