You have to understand that the 4000 is alot different then the 3500. The 4000 operating frequency is 2.4ghz. So OC a 3500 to 2.4ghz would be very simple. Althogh theirs nothing you can do to gain 1MB L2 cache..
I've seen one article (dont ask for link, just random one about winchester vs newcastle) and both CPU's hit 2.7GHz on air, however the winchester got closer to 2.8GHz and slightly lower temps.