It hides incredibly ugly gaps and irregularitite s in the sealer if not one of the all rubber seals. Add to that the possibility of cracking the glass when removing the clips if they happen to be firmly entrapped in the glue there. You WILL have to cover it with something else when done, it looks way too bad. No gasket, rather a tar rope seal that stuffs in pretty messily.

79-80 windshields were slightly larger & glued in. Get a late windshield & fill the remaining gap with some metal welded in then glue the windshield using the rubber trim late model cars use. It's some work but could be done.