Had to do this on my '84 Monte SS. I was unsure of my abilities to remove/prep/re-apply the fabric nice and wrinkle free with no glue seep through/messes without damaging the cardboard/foam like backing form board. Also didn't think spray cans of contact glue would work well. The entire backing form board and fabric must have enough but not too much contact glue sprayed on them and you get one-shot to try and lay the fabric down. I removed the headliner and took it to an upholstery shop and had them do the fabric and sunvisors, was about $125 or so. You can also buy a new board with fabric for just under $200.
(Example:
http://www.automotiveinteriors.com/a...evy_camaro.htm)
You have to pop off and remove all the trim around the headliner; at windshield, rear window, over doors, a pillar covers, c pillar covers, sealtbelt anchors, domelight etc. It should then drop right out. If the seats don't recline/lay back they may need to be removed as well. As they say on Wheelers Dealers, it can be a bit fidgety. Just need to make sure you don't fold/break the flimsy backing form for the headliner. I think the shop wanted about $350 to do it all.