My right side vent window is missing the latch...and I'm sure I know why. I have a correct NOS latch, but how do you install that? It looks like the frame has to come off the glass first. I'm sure I'd trash it if I tried. Is there a specialist out there that would take this on?
You are the "specialist". You can do it. All you have to do is put some duct tape, a thick rag, or rubber on that glass and pull it out of the frame gently with a wide clamp or pair of pliers. One of those vice grips with the wide mouth for shaping sheet metal would probably do an excellent job. You might be surprised at how easy it will come out. Then drill out the broken latch piece and pop-rivet the replacement lever in place and tap the glass back into place with a rubber mallet or something similar. If you break the glass, it's no big deal. Just order a new piece.
Post your location specifically (not just the state), and there might be someone nearby to help if you still don't feel comfortable with it.