Had an 83 Dancer with the shag ceiling cover. It was an inexpensive way to cover the rough side of the fiberglass (the ceiling and anything else you needed to hide) I tore it all out and glued a heavy burlap looking material in it's place. I used 3 M super heavy duty spray adhesive on both surfaces, let it tack and then stuck it in place. First sunny day the ENTIRE ceiling job fell to the floor. Was a sad day.
Subsequently, I bought a couple of gallons of odorless carpet adhesive and a paint roller (stop me if you've already heard this). I rolled on a really thick layer, let it tack and believe me that material is still in place. Bad news is, if you drip that carpet glue on any upholstery or soft material, it is almost impossible to clean up. Tarp everything first. Just some FYI for when you get the old fur out and start the replacement process.