Here to help with the not-so-many pics I have.
The front, hard headliner part and the flexible vinyl headliner is held in place by a shiny U shaped trim part that surrounds the top of the door. It runs from the corner of the wood dash upwards to just below the forward point of the ceiling grabhandle.
The u-shape pinches the headliner material over the body flange.
in pic 327 you're looking into the cabin from the right side. Close to you, on the left side of the car, the trim is out, In the back you can see the trim still in place.
pic 531 is looking up in the right door opening, at the 'b' pillar point. It shows the connection clip.
The front the hard headliner part is also held by the screws of the sunvisors, and 2 small rivits on each side drilled into the body flange at the door opening.