Need help fast with vent window

You have the replacement, I posted some pictures of how it is attached, you will have to decide on how to install it.
to remove that vent assembly will cause quite a bit of work & more $$ spent in the form of cat whiskers.

I do not know the condition of your parts --but when you weld will that not discolor the chrome?

maybe braze them in place?
spot weld?
very short flat headed screw?
for that matter remove the head of the rivet carefully & you will have a stud to mount the new pivot?
options are out there, Lawrence