I'm 6'4" and plus 230#. My concerns would be the top tube only because of ease of denting? and the head tube/steerer length. Unless he wants to have a large seat top to handle bar height distance he will probably need a fork with a 350mm stem and longer head tube to limit the steerer spacers. At 6'4" my handle bars are 3-4 inches below the top of my seat with an uncut 300mm steerer tube. There are carbon forks with a 350mm steerer out there.
You can buy 44mm head tube material in 2 foot lengths from Nove, Bike Fab etc.