Would get a better cooler, when you OC with that, in effect you are OCing the whole system as you OC via the FSB, so want to keep the CPU as cool as possible, 3.6 is rather common (FSB to 1600) and many head it on up to 4GHz
But there is a risk, yes 400FSB can be reached, and is one of the stable areas, apparently 400 is easy, but 350 is hard for instance. Anyway, I killed a mobo trying to OC a E6600, no warning, just smoke. I don't believe you'll see much benefit, for a low probability high impact risk.