If Grace comes in anywhere around 220, he'll get a ton of playing time, may earn a starting spot by year's end, and lock down a position for years.
He's a natural LB. In the last 12 of so years, it's Rocky Mcintosh and Sean Spence as natural LBs. Grace has more range than both and a higher upside than Spence because he's nearly 6' 2" with long arms. He's probably not going to be as good against the run as Rocky was...at least early on. But, the game has also dramatically changed in terms of what is needed.
I would put Perryman in that class as well but I agree, Grace is going to be the real deal. I'm no film expert but when you watch Grace away from straight highlights, he moves through traffic and reacts almost effortlessly, like he's on rails. But even for a kid that played a bit undersized he hit with ferocity.
The game just looks like it comes easy to him. Just needs to keep working hard so he's ready for the physical battle at the next level.