Ivy Bridge doesn't overclock as well as the Sandy Bridge so it would be better to wait for Haswell and see what that can do.
If you absolutly can't wait then the Sandy Bridge E would be a better choice than Ivy Bridge.
There is also this card to consider and it would add to the performance of your Pc. What you can consider doing is to swap out the video card and keep the 460 so that when Haswell comes out and you decide to go for that cpu , you could put the 460 back in and put the newer card in your new build.
I would also not run your current cpu at that voltage as it will shorten the life of it , If you go over 1.38v for an extended period of time it shortens the life of the cpu and if you want to give it to a family member then you would want the cpu to last a while longer.