I can't speak for other states, but I can tell you that Mississippi did not title vehicles built prior to 73 or so. I bought a 67 Mustang in 98 from a fellow in Jackson, MS. who was the second owner. He had bought it from the original owner in Alabama where a title was never issued either. When I bought the car, all I got was a Bill of Sale and the Mississippi Registration. When Broadway issues paperwork they send you a Notarized Bill of Sale from a Licensed Dealer and an Alabama Registration. In Louisiana thatis all that is necessary from states where titles were never issued to vintage cars. In Arkansas, I'm told you can go the bonded title route. Same thing in Texas I believe.
If California is not accepting this paperwork, then buying a vehicle from a legitimate owner in states like Mississippi and Alabama must be impossible.