Headliner and weatherstriping questions....

Your original headliner should be a thin, pressed board style molded to the proper shape. It is held in place with a few clips on the roof rails under metal trim pieces, and it may have a single screw holding it up to the roof framing just above the rear window. Of course, the rearview mirror holds the front edge up to the roof.

If yours was replaced with something else, it's possible to find one in fairly decent condition, but good luck - they are fairly fragile after all these years.

There is a company that reproduces them in ABS plastic, but I can't remember the name. I can't speak for their quality because I've not seen one.