Any bike he gets WILL need suspension upgrades. Stock springs are set for somone 160ish pounds.
A KLR/DR650/DR400, etc has the power to support that mass. It will be long enough in the leg for him, though he might want to look into a custom seat. From what I understand, power is easy to manage so long as he is light with the clutch (lots of power at the bottom revs)
Sportster 883 is an option. Very standard seating, with the option of highway pegs up front to let him stretch. Again, enough power to support his weight.
But seriously, a Dual Sport with upgraded suspension. I’d look at the mods long distance guys do to thier KLRs to handle the extra weight of their gear, because I’m pretty sure many of them end up going over the original weight limit.
“The two seconds between ‘Oh S**!’ and the crash isn’t a lot of practice time.”