1966 Dart GT Roof Trim Help

This is why I didn’t remove the clips back in ‘75 when I repainted the car and in 2018 when I changed the color .
I see no reason why you can’t screw the clips down from the outside, just move them over a bit and drill a pilot hole and screw down with a stainless steel screw .
If you’re missing a few, just space them equally.

You do not want to remove the headliner unless it torn and needs to be replaced.
This requires removing the windshield and the rear window and all it’s trim plus the weather strips and trim on both sides of the roof this is a lot of extra work and extra expense that can be avoided.
So the trim can be released from the clips but they are attached from the inside out? If so, could you drill out the fasteners and pop rivet the clips on the skin? Just thinking outloud.