I think there have been some powerful 5/8's with Wally and Filipaina ect....thing is if he has the agility to play in the halves, his size is only a bonus, so is not a problem.
The fact he has the size and ability to play in the forwards is also good, as depending on the halves options at the time....a roving lock taking on both sides of the ruck adds extra threats.
Get with the times fellas ..... we have 6'5 and 110kg wingers ..... every position is getting bigger and the difference between forwards and backs is becoming negligable ....
Within a couple of years you won't get a look in at 5/8 unless you are built like a brick outhouse and can defend the edge ....
PSS .. Unless they reduce the # of interchanges ... then ignore what I just said....