I agree with Bud. He would have some wins, but when one of these wrestlers who cuts to make 265 rolls in they would probably steam roll him. I think his striking is superior to all of the HW's, but it is hard to stop a takedown from someone who outweighs you by 60 pounds or so. Sure Couture stopped Lesnar, but he had a lifetime of experience from wrestling helping him out.
I agree in that I think IF they get him down, they would cause him quite some trouble, BUT the question is, would a 265er be able to move his bodyweight fast enough to catch a 230 Silva¿ Dos Santos stops most of the take down attempts by just not being there anymore, because he has good distance management.
Silva doesn't even need much more power, because the beauty (and effectiveness) of his strikes is their timing and accuracy which are even better than Dos Santos'.
So I can see Silva making quite some noise at HW, with probably Velasquez and his fast shot giving him the most trouble.