Hello ,
I am 6'1 and all I can say is that for me there is not any problems in airliners ( 737 & 320 ) , but however without being fat ( 85 Kg ) it's true that some of the General aviation cockpits are small ( TBM 700 ) and difficult to move into :s .
i would agree saying that 6'2 is the maximum , at least for general aviation .
It's also important to keep working out and have a good diet because to " feel " good in your body is essential . I know it's difficult as we're always on the go but it's an effort to do . I would also say that since i work out each day I feel a lot better both in my body and in my mind , working out is a great way to " clean/wash " your mind and so be more efficient
Regards
JBB