I've done that job twice. Each time I called around, including to Moss, VB, etc., and to local shops. No one suggested using spray adhesive. In fact once the windshield is secured the more important adhesion is for those forward flaps that tuck under at the front. Each time I opted for adhesive applied a little to the top surface (underside of the dash covering), along and the flat lip that goes under the windshield. That adhesive was some form of silicone from a gun, and I just can't recall the specific kind--but it was not a spray on. Then, for the front lip most people recommended a contact cement, and that's what I used. I bought some cheap Stanley vices, and using cloth and wood strips, I just left it all together overnight. You will want that front profile to stick and hug tightly to the steel dash surface so there are no wrinkles or imperfections. There are no strict rules; I probably didn't need to put the windshield back on right away, but that seemed appropriate since it snugs up with the various dash and underside fasteners. My opinion is that adhesive on the top surface doesn't do much, and when I removed my old one--what a beautiful preserved paint job I had on that surface. I felt bad even applying adhesive which I did sparingly.