Damn, 6'8"....
Well, to be completely honest with you...I dont think your ever going to find a sportbike that you will be completely comfortable on. Sportbikes are not designed to be comfortable to begin with. Everyone talks about the comfort factor on sportbikes....I say fuck comfort...if I want comfort, Ill go buy a Goldwing or just drive my car. Sportbikes are high performance machines...comfort is not a high priority factor when they were designed.

Being that its your first bike, I would stay in the 600cc class....even though you are kinda big. Ive riden four different 600cc bikes...a 2000 CBR F4, 1997 Suzuki Katana 600, 2000 Suzuki GSX-R600, Yamaha YZF-R6.

I would have to say the GSX-R was the most agressive/uncomfortable seating position, then next the R6, then the F4, and lastly, my first bike...the katana was the most comfortable. But the katana was the slowest compared to the others. You should just try sitting on a bunch of different bikes.

I would suggest yoga if you are really uncomfortable on bikes and still wanna ride.