After obtaining a solid and clean mounting surface I covered the entire cabin roof with a single layer of Dynamat.
I used a heat gun to preheat the roof to enhance adhesion and covered all seams with 2 inch HVAC aluminum foil tape. Lots of roller rubbing to remove air bubbles and maximize adhesion
for headliner I chose a commercial foam backed headliner material in black and aerosol 3M headliner adhesive.
I successfully did a minimal amount of masking, as I always used a cardboard edge guard to confine the spray as I proceeded gluing the entire piece, starting at the center of the windshield.
I used a heavy steel straight edge to hold the rear of the headliner on a suspended plywood shelf. Followed adhesive instructions carefully working section by section down the center and to the sides
Cut the excess fabric from the purposely oversized headliner and did a lot of firm but gentle pressure rubbing to maximize adhesion.
car now has about 1500 miles on her, about half of that in 90°-105° California sun. No sagging or smell from the Dynamat
Larry