One of my leadout guys, in the early 90s, was about 6'6", rode a 66 cdale with a 400mm mtb post at max height. I rode a 50 cdale back then, so the opposite end of the size spectrum.
I found that I needed a guy between me and the leadout guy because, frankly, drafting knees doesn't do much for me.
btw he's the one I went to Belgium with, and he was very strong for a year or two.
cdr