I replaced our 73 Mustang Mach 1's door glass (both sides) a few months ago, and had to deal with the rivets. I dug up and used some bolt-in hardware from some 71 & 72 Mustangs, and used those for the reassembly with new glass. I got our new glass from ECS Automotive Concepts. They were able to etch the correct logo of the glass manufacturer, product code, and date code into the glass, so it looks like factory glass.
I also made some YouTube videos showing how we relaced the glass, to include how we dealt with the rivets when disassembling and removing the old glass, and show how it was all rebuilt using the bolt-in hardware. It was a fun, but tedious, project. And well worth the effort.
The reason I replaced the glass is because over the years the outer sides both got scratched up a bit, too deeply to polish out. So, I ordered new glass.
Here are the links to the videos:
https://youtu.be/2B5zPGDBznU
https://youtu.be/DXpAOKkxxZU
Lynda and I have made over 150 videos on how to diagnose and repair these First Generation Mustangs and Shelbys. My YouTube channel is:
https://www.youtube.com/results?search_query=gilbert+hale