Sio Moore might be the best option at MIKE and as a 3-down LB. I know UCONN used him all over the place, but I like what he did on the inside. He definitely has the ability to be a half-field LB. He's got ideal size, he's extremely versatile, smart, strong, has great athleticism, and fights through blockers well.
Only problem is, I doubt he'll still be on the board at #58.