A definate maybe. :D
Clair should be able to provide more info.
My impression was the seats were original to the car.
I don't know if he had a build sheet for it, but might.
Another clue may be if the seats have a latch - most (all?) 67s don't.
If we can find some examples of '68 bench/split bench headrests, that would be another point of comparison.