If I recall correctly, the '68-'75 Nova used the rear steer design, then went to front steer in '76. I wouldn't think parts would be too difficult, as many swap with Camaro, Chevelle/Malibu, and even S-10. I do knw one of the other reasons for the earlier subframe is that it's a little narrower than the later ones. They fit better under an AD truck.
