I have the 513s on my RK since May of this year and like them. I am also 6'3" and they are much better than stock. However, I am going up a notch to the 515s, plan on install on the weekend of the 16th. I will have the 513s up for sale if interested.
I have 513's on my RoadKing and I'm 6'1". The fit is great, but that has to do with the fact that I also have the Brawler seat as well since it has lowered me about an inch.