Today I replaced my sagging, torn, slashed, terrible looking headliner on my 92 88. I got the foam-backed fabric from Jo-Ann'* and used 3M'* trim spray adhesive. It seems durable but hasn't withstood the test of time yet of course.
I'm not sure if they used a different process for 92 88 headliners or if mine was just really rotted away somehow, but wire brushing (suggested by most write ups I looked at) was not helping at all. I had a LOT of foamy stuff still on there. What really sped along the process was a plain old putty knife. It pulled the rest of the headliner foam right off the board.
Now underneath this was the board and it wasn't really foam, it was some kind of fiberglass insulation -- I was getting insulation splinters before I realized I needed gloves.
Before and after pictures attached ... I did the pillar supports too. They were real bad. I haven't put anything back in the car yet since there'* a little rust spot on the ceiling starting from the inside that I want to address first (I'm waiting on my Chassis Saver order from Magnet Paints).
One of the pillars before I started ripping things out (not sure if that'* what to call them):
Pillars afterwards ... brand-new lookin:
Right after pulling the board out:
And the new headliner ... ta-da: