I feel your pain, old57. I'm 6'4". While experience and opinions abound, unfortunately you won't know if you like what you just ordered and installed until you go for that first ride, even if the person who recommended it is your exact height. They're not cheap so I would advocate finding a place with a liberal return policy in case you don't like what you try.
I tried a Madstad Adventure adjustable windshield, which I believe is about as large as any available windshield. I will admit I liked it in the rain and it did keep the bugs off my helmet visor, but other than that I found it cumbersome and annoying so I took it off. It was never truly effective until I kind of hunched down behind it, which I rarely did.
I currently run with no windshield at all and that's what I prefer. I get a nice, smooth flow of air that doesn't bother me even at higher speeds. I also get more rain and bugs in the face, but I can live with the tradeoff. All the buffeting coming off the factory and aftermarket windshields used to annoy me: now I don't think about the wind at all. Plus, it's actually quieter without the big windshield.
It might be worth temporarily removing your factory tall windshield and riding without it and seeing what you think before you delve into the world of tall aftermarkets.
This is my current setup: it's the mounting plate for the Madstad windshield installed in place of the original windshield. It looks taller in the photo, but it's actually just about the same height as the surrounding fairings.