I just ordered 2 of the MadStad windshields. One for my wife's NC700x and one for my NC750x.
They have a size chart on their website to recommend the correct size.
They were very helpful with their recommendations when I emailed them and told me that they do their best to recommend a windscreen that has the top edge below the riders eye level so you comfortably see over the top of the windscreen. You may want to contact them directly for advice, which is what I did. Sounds like you might need a 16" tall windscreen?