I have a 91 Formula, the factory headliner was in great shape...
Took it out and had it fiberglassed, reinforced, etc...
I was going to reuse it with a custom fiberglass console, but now it's not very flexible, so I will need to go the aftermarket ABS route....

The plastic pins in the front were still in place, so I had them glassed / reinforced too.
I would probably sand the bottom / shiny side before trying to glue headliner material.
If yours is rotten or gone, this will be a factory fit, since it is a factory headline that has been fiberglassed.

I have $180 in time / materials, not including the headliner itself.
An ABS aftermarket headliner starts at around $220... They do not fit as well as the OEM ones, but since I'm mounting a large custom fiberglass console, it will hold / cover it up mostly.

$180
Locally listed on Craigslist too...