I've messed with windscreens quite a lot and, like everyone else, can only offer vague suggestions. Some things I have learned:
How tall one is, is unimportant in comparing windscreen heights. Go by how high your helmet is above the seat. I'm 5'7" but taller seated than many of my 6' friends.
Windscreens for most people seem to work better if one looks over top of the windscreen.
It is important to qualify what windscreen feature is the most important. Is removing wind loading from the chest most important? Does the windscreen need to deflect bugs and rain from the helmet? Do you require that the helmet be in a dead air zone or is it better for the helmet to be in non-turbulent moving air?
Placing the helmet behind a windscreen will often result in much more noise which can be a larger issue than other effects. I used to have to wear ear plugs with a taller windshield but they were not needed with a lower one.
Wind onto the chest can be very tiring over hours of riding and some cannot tolerate steady pressure against the helmet.
I'm hoping that someone will offer a formula to better assess windscreens but over 50 years of using windscreens and fairings have left me with the conviction that one needs to ride the same model bike with the windscreen in question.
I made a 14" (above fairing) one for my bike from a piece of 1/8" Lexan for a few dollars. If it seems to offer some improvement by modifying, I can snip away or buy another piece.
Laminar lips add another dimension and there are legion home made versions which might be worth the experiment.
Try clamping a piece of heavy cardboard or plastic to your present screen to see what are the effects and whether they seem to benefit.
Suggesting that is a bit selfish on my part as am hoping to hear of results. I'd like to think that 1/2 the people here are smarter than I but think it's much more than 1/2 so likely someone will have some valuable observations.