Dave,
Dante's Mopar parts sells the 73-76 style headliners in ABS plastic. He advertises on Moparts and you should email/call him and ask about it. His latest versions are supposed to be pretty good and he now makes them them for sunroof A-bodies also. You won't be able to find anyone reproducing them in the cardboard like material.
Remember I had to custom make one for my sunroof Duster years ago as no one reproduced a headliner back then. I glued marine vinyl over a corrugated plastic like material. Finding a suitable backing material large enough is the tough thing but two pieces may work ok also. My headliner is pretty much like a hardtop one except it's flatter or doesn't curve as much in the middle due to the sunroof panel plus it's got a hole in it of course!
I can stop by sometime and hopefully answer some questions you have about a possible swap. Plus if you want to take a closer look at mine feel free to stop by anytime we can get together.
Cya, Brian
