Consider that a modest 3" heel visually reduces your feet size and makes wonders to your gate and posture.
You're taller than the crowd regardless, in heels or not, you cannot change it, but you can embrace a supermodel mindset.
At 6'3", my favorite heels are 3". Anything less is boring, anything more - tough on my feet and doesn't improve my appearance or presentation (I've worn 5"heels, but did not like them).