I got my headliner out of my coupe in one piece and it was a PITA. The main problem was that it's glued to the underside of the sunroof tray. I was able to work it loose from the back with a thin, flexible, handsaw just pushing through the adhesive with the end of the saw.

That being said...your 90 doesn't really give you that option, since your rear windshield is in the way. My vote is for a rear fender mounted ant. You stand to lose too much by attempting a removal.

Just my $.02
Jake