I think the X-Factor for the Chiefs should be McCluster. You, yourself, said that the Colts are weak against the edge run, McCluster is the only guy that really brings that. Obviously, Charles would be perfect.....
I'm not really sure about Painter because, while he did make some plays, he didn't have the greatest completion percentage in the world. Of course, if he goes to Clark early and often, he'll have success. The reason being Washington and Piscetelli will be on him, and they're both terrible.
I agree that this is a toss up and will come down to which of the coaches have the better gameplan.