Eric,I tried to glue it to the headliner and that didn't work. I didn't know if I could use some padding in between the bows and glue it to the rood and then get the new headliner to glue to that and if it will hold or not.
I'm planning to do a custom headliner too, and have ordered a stock replacement and will either sew the new fabric to it (at each bow seam) or use the stock one as a pattern for the custom one. I wouldn't trust glue to hold much for very long, unless you were going direct to metal or board.
(BTW -still looking for those glue strips next to the windshield )