Well there are a number of defensive tackles in Free Agency this year.
Obviously Willfork is one of the biggest since he works in a 3-4 this would tend to be the best choice for the Chiefs.
Richard Seymour, but I always saw him as more of a 4-3 type tackle. I don't think he has the size to play nose tackle and would be better suited as a DE in a 3-4
Aubrayo Franklin - San Francisco
This guy might be a good pick up, he has done pretty well in San Francisco so we will see. We could do a lot worse and he is definately an upgrade over the guys we have.
There are others, Casey Hampton, Ryan Pickett, and Tony Brown, but those guys are likely to bring more money than they are worth.