I'm 6'10" and 350, and I run Aerotech bibs exclusively now. This model specifically:
Aero Tech Tall Man Cycling Bib Shorts - Extra length and Long Inseam It took me some time to get them, but they're absolutely worth and I'm really happy I bit the bullet and bought them. And frankly, there are much MUCH more expensive bibs out there. By comparison to some of the high end bibs, the Aerotech's are a great deal. Good luck and happy riding!