650 makes a claimed 71 hp.
Weighs a claimed 383 pounds dry.
400 makes about 60-65 hp depending on tuning, exhaust, etc.
Weighs about 378 pounds dry.
Now those are just some specs to think about, but at this point, it mostly comes down to the rider. The only other thing I'd think about that would go to his benefit is the low end of his engine. The lil' bandito can be a bit peaky and makes most of its power up top.
Depending on how long and how good of a rider he is, I think you could take him, but it's really anybody's race.
I vote FZ6.... 110 dynoed hp