That's not going to be an easy task...Most very tall riders I see around here, have either custom made bike, or a very old/vinatge road bike.
Check craigslist listings...I see bunch of HUGE road bike frames on it every month....like this one .
Specialized is also making XXL frames, so it should be a good size for 6.6 rider. I'm 6.3, and I ride on their XL frames.

Good luck