I cant help you with the top or bottom rails but there is a company that is making them now here in the US. I have seen 2 of them that have come from them and they turned out great. They are made to order so there is some lead time on them.
Here is the link to them. It says it is for a vking but the Viper, Vector, Vking, and Vulture all use the same windshield.
https://www.updplastics.com/hydrostream-boat-windshields/
Hope that helps some. Also, these are not drilled and some very minor trimming may need to be done. I know one person his pit perfect right off the bat, the other needed just a hair trimmed off the top so it would sit all the way in the top rail.