I'm 6'-3 & was getting hammered on top of the head too with the stock shield. Got a HD "Tall" windshield, which is a couple of inches higher than the stocker, and no more banging on top of the head.

 

Klock Werks has a "try it before you buy it" program. On there website go to the dealer locator, pick your state and you'll find a list of dealers in the program. You get the shield put on your bike for a test drive and decide if it works for you. When you decide you get a new one in the box.

The only real way to know what windshield works best for you is to try them. If you don't like it it only cost you a your time and a little gas.