Most if the 740’s I see seem to have had issue with the cloth headliner falling down.
Last summer I stripped a car and I saved the cardboard it did not have a sunroof but I have cars that do.

My intention is to replace the cloth then swap the whole cardboard in to the car I’m hoping to fix up
Doing that from in the car seems difficult at best.

I thought I might paint the headliner cardboard with colored epoxy maybe put cloth on that but it will make it more rigid..

If you want to remove it what I see getting stuck upon is the vinyl covered trim near the windshield and edges I found that plastic had seriously degraded and if you can get it out and back again you’d have to use extreme care and maybe be a bit lucky
I do not know if it’s available and any wrecker will likely have that issue too.

If I remember right there is some trim around the circumference if the sunroof and that may retain it ? It will show in the parts book I can look if you need I have the blue book somewhere here.

If there are better ideas than pulling the cardboard I’d like to know. It’s not an easy task for sure. Especially when you see how brittle that plastic gets .

If you pull it, it might be worth trying to do the same at a wrecker if you can because there might be techniques to practice and perfect. ;)
Amazonphil