Hi Edwin,
I have a set of these opening 'quarter' windows. They were used here in Australia on the earliest R4's, assembled in either Sydney or Melbourne. Post about 1964/5 they were replaced with fixed glass, and the rear door glass, which had been fixed on these earlier cars, was made into the more familiar two sliding pieces.
Do you realize that the body work around those opening windows have small recessed areas where the hinges are mounted to the body? They are about 5mm deep [on the back edge of the 'C' column], by about 20mm long. As I am restoring my R4 as a 'standard' version circa 1962/3 [with a fixed metal panel blanking out that window altogether] I have mine surplus to requirements. I could sell them to you but given the weight of glass the freight from Australia to the UK might be hefty.
Perhaps, if you are able to help me out with a 3 spoke steering wheel from a1962/3 R3/4 I would be more than happy to do a straight swap. Steering wheels come up from time to time on leboncoin, but so far I have had no luck getting any responses from the French sellers. I don't think they want to be bother shipping this far.
Don't know if the above has helped. Good luck with your plans.
Ron