TP to the OP...I think that he has the physical tools to play the 3/4 a la Jeff Green and Rashard Lewis.
In June, NBDdraftnet thought so too:
Strengths: A long, tall forward with good scoring instincts ... Is a legit 6'10" in shoes with a long 7'2" wingspan ... Has very impressive leaping ability with unusual explosiveness for a big man ... Tied for having the highest maximum jump reach in the 2011 NBA Draft Combine, getting as high as 12'1.5" ... Frequent target for ally-oops and lob passes ... Very agile and mobile ...
Has the speed to play the small forward position at the next level ... Really improved his scoring ability every year he was at school ... Has a smooth and refined turnaround jumper, which is very difficult to defend due to his length ... Has shooting range out to around 18 feet from the basket ... Has become a real threat in the post ... Nice-looking hook shot from the left side of the rim, with a soft touch and a high release point ... A factor on the offensive glass, gets a lot of tip-ins and put-backs ... Great free throw shooter (80.9%) that gets to the stripe a lot (209 attempts in 2010-2011) ... Moves his feet well on defense ... Big-time shot blocker, averaging 2.3 per game ... Had a successful 4-year career at Purdue ...
http://www.nbadraft.net/players/jajuan-johnsonPlus he's a lot stronger than either of those guys.