Some part of Taylor Made (http://www.taylormarine.com/windshields/index.html) has made a lot of OEM windshields for lots of brands of boats. So, I'd start there to try to get lucky with something they may have already made and might be able to make again.
That said, I think some people here have tried that route and failed with other Donzi windshields. So, I wouldn't get my hopes up.
A couple other places I once found on the web are here:
I have zero experience with either of these, but it looks like they do the sort of thing you are looking for. Looks spendy though..
My best luck happens when I search Google for something like "custom curved boat glass windshields."
Good luck, interested to hear what you find,
Mike
"I don't have time to get into it, but he went through a lot." -Pulp Fiction