The 64 sedan had 3 point lap belts and a roll cage reinforcing the passenger compartment. Not really a particularly compelling example of a typical ‘64 sedan…
The coupe is a close to correct C-code, which I've driven under 1000 miles in the last decade, so I've decided to leave it with period-correct 1965 belts that a prior owner installed rather than modify the B-pillar as my exposure isn't very high on that car due to very low annual miles.