Early A-Body Windshields, good purchase!
It was about 80 degrees here so I replaced the windshield. Getting the old one out was easy. I removed the lock strip, then got the wife to get inside and push it out with her feet. I caught it, and no damage.
Then cleaned the original seal and body edge. I also removed the interior trim, to give working room.
I placed butyl caulk tape that measured 1/4" x 1/16", around the opening and installed the gasket, and got the wife to help hold one side. I set it in the bottom, then pushed the gasket back at the corners using a plastic pry tool. I took care to only make adjustments to the gasket, without contacting the glass. I worked up the sides, top edge was last. I then replaced lock strip, by inserting one side, then used tool to pry back gasket while pressing on lock strip.