Yes - it will cool it down. All heatsinks will cool down a CPU - it's the purpose.
Will it keep it between your current range? No.
Should it keep it within operational range? Hard to say.
Will it stop it from melting a hole through the mantle layer of the planet? Not sure.
The best way of knowing this - due to the thermal dynamics and fluid dynamics (air) of your system is to begin overclocking in steps and see what you can do.
UPDATE: I am not sure that this CPU will get up to this level with your system and memory (which are not stated.) Repeating what SR-71 Big Air or a water cooled system is reccomended for this ambitious of an overclock. Not sure what you are trying to accomplish here - but a good game of Pong only requires a minor overclock of this CPU. Go Pong!!