No real difference between the roof of a 71 & 72, though some 72s had a pressboard headliner. Some of the cloth roofs had five bows others six.
Like many who have already responded, I don't think I have what it takes to install a fabric headliner. The ABS repops don't seem too bad. You will need sail panels, though.
The Demon has a six bow cloth roof that I farmed out. I had considered the one piece route and had made sail panels from artist board. If you need a pattern, send me a PM.