you can get an older carbed cbr f4, they got the banana seat and great bike to start riding. But I don't know how much you weigh if you're like 6'3, 350lbs then I dunno, it might be like riding a pocket bike.
One of my friends bought an RC51 as his first bike, and hes like 6'3 about 370 or something, but he's pretty damn big....
and my friend that was about 5'8, 170lbs, was able to keep side by side with him on his sv650, and they're both pretty good riders...

You could also get a TL1000r, they're pretty big bikes, and they're v-twin so they're pretty smooth to learn on.