70 Challenger SE Headliner Help

[70 shaker challenger]

Car is very original and has a black felt like headliner that is starting to fall down.
All the things I see on headliners talk 3/4 ribs .
This is not a rib style liner it’s smooth and glued in.
Need help to fix. Can I glue back up.
Roof seems nice and smooth with no insulation on material sagging down.
Glen

 

[NixDad]

You obviously have an SE, as that has a different type of headliner.
Is your objective to replace the headliner or just fix the sagging? To just fix the sagging there are various adhesives, but not all work in the hot environment of the inside of a car. You could go to a trim shop to have them glue it.
If you want to replace it, try SEHeadliners.com