If he's at 205 right now (I think I heard he was around there) with another 10 pounds, he's the same size as DeMarco Murray, bigger than Marshawn Lynch and Lesean McCoy. Those guys were all around mid-4.4 in the 40 at the combine - I don't see any reason why Jamaal can't hit 4.45.
Rob Rang said his skill set translates nicely to the NFL.