I'm 6'6" and its pretty miserable. How do you have your seat set up?
For street driving its pretty survivable. But with a helmet on my head is firmly planted on the roof, making the movement for looking around on the track more effort and the extra height from the helmet is keeping my arms almost fully extended.
Non exact measurements are
28" shoulder to first knuckle
40" butt to top of head (nearly) so add a couple to get the helmet height in
46.5" heel to back of butt