Very very hard to find. After searching for years (was in yards a good 250 days out of the year for over a decade), also examined several nos Nova and pickup vinyl floor sections I had picked up from numerous dealership buyouts... never any nos '68-72 Abody sections, though
After basically searching to Hell and back, stumbled onto a nice pair for one of my keepers. Crazy thing is: years ago, in my HO GT-37, after finally finding those replacement vinyl sections, I was in the garage pulling the seats to measure them for nos fabric reupholstery. As i removed the bench seat, there was glimpses of the original vinyl flooring under where the seat tracks had been bolted. The original owner had used a local trim shop install carpet. This shop took loose 80-20 loop carpet with a very fine gauze like backing and GLUED it with contact cement onto the original vinyl flooring. It was a surprise, but was an absolute nightmare to remove from the original vinyl sections.
As far as styles, there are actually two different style grain structure vinyl flooring for '68-72 base A bodys. part numbers are also molded in on a small flat pad by where the front seatbelt retractor bolts in. From what I've noted there is basket weave style vinyl flooring, and a pebble grain that looks more like "melted" small pieces of gravel. '71's along with the '72 2door post LeMans had the latter style. Out of '70 Chevelle 300's and late '70 T-37's I've run across the basket weave style.