i may be fat but at least there is 20 stone pushing it in...LOL

big is best,..yes, or so i keep being told, haha, oh and dont for god sake buy an older 600 it will be slowass with your weight on it.. a newer 600 yea, might be worth it.
you could get a decent ZX7R 1996-7 for a little over 1K make you a great mint first bike.
also they aint slow with a bigger guy, you may need to change a few suspention bits for your size but if you need any advice then i can help with the kwaki..