Hightower is "projected" to run a 4.85 forty. That would be ok for a 3-4 OLB but too slow for 3-4 ILB. A 3-4 ILB needs to be around 4.7 or better. I don't want another Bradie James type of player that is good/great against the run but a liability against the pass. The combine will be big for him.
He "might" be great as a 3-4 OLB, but do you want to use a 1st on a player that needs to change positions?