On the surface it makes sense for you to acquire Kane and him to acquire Callahan.
Callahan is more dependable, while Kane has a higher risk/reward factor. Kane could payoff big in Buffalo, but I don't think it'll happen right away (Reinhart and the 2015 first rounder will both be rookies). But you could argue that Kane for Callahan by itself would be an even swap, given that Kane's ceiling is higher than Callahan's.
It's kind of a crapshoot depending on what you get for your second round pick. (I'm surprised he's after prospects if he's chasing the title right now, though.) Will this second-round pick be worth the prospects you're giving up?