I agree that you have to do something with NT, but I'm not sure what. I think the ideal player is somebody who is more stout against the run and able to command a double team, but also able to provide a pass rush, or at least an inside push. Who that guy is, or where you find him, I'm not sure.
It's a shame that Ta'amu is no longer in the mix. He started some games for AZ, and has ideal size and power.