I'm 6' and mine's a 10" Halfmoon Wings and it's perfect!!
http://www.customflhtwindshields.net

 

I am 6'3" with an 8" standard shield and still get alot of buffeting. I am going to run the 4" in the hot summer months and get a 9 or 10 for the cool weather riding seasons. This is my first bike with a wind shield and honestly like the no wind shield better than all the buffeting from this bike. You go to the point of no buffeting and "I believe" you might as well be in a truck because you will not get the feel of riding. Just my opinion.

 

I would suggest looking at either Clearview or Cee Baileys and get one with a recurve at the top. The recurve allows you to go shorter on the shield and still get the effects of a taller shield.