Try this site. It is a Ford but helped me do mine.
I used a top from a outlet in Conn. Not exactly like the original. I did it in the warm weather and a little sunny out to make the top soft and flexible. Tacked one end in the middle then stretched to the other end and tacked in the middle. Then the sides same way. Then just kept working all atound.
Then cut it on the metal recess. I useed a tack at each end of each slotted hole. I left the center of the slots for the trim. I used clear silicon for a sealant uner the trim and lapping the vynl edge. I hope never to get caught in yhe rain.
http://abarnyard.com/workshop/roofinstall-1.htm I don't know what hampton coach supplies for going under the top. The kit I used only had 1/8" foam and I ended up having to beef that up from inside as after a while I could see the outline of the slats.
In your case you want to be sure about this as you already have the headliner in. Good luck, Bob.
