Has anyone heard of a company called formed plastics? I just recently found out about there company who specializes in replacement globes and refractors for older style streetlamps. Apparently if you check out their catalog online they sell a polycarbonate Westinghouse OV20 style refractors. I think anyone who is restoring streetlamps should check out their site.
https://formedplastics.com/ is the web link. Click on the lighting store tab where you can find all their products and their pdf catalog showing more off what they have.