I'm going to hold off on this until I actually see them both in the ring, throwing punches. You never know when this will turn out to be false.
But nonetheless, I think Mirko is big enough now to handle JLB's size and work out a TKO in the 3rd.
PS: Anyone seen their first fight? It's hilarious, it was in 1996 and Mirko must have weighed no where over 200 lb. And his name at the time was "Mirko Tigre"