Should be easily obtainable if your mobo will allow you to OC, which it should unless this was a pre-built. Off hand I think the max OC's people were getting from these CPU's were 3.2-3.4ghz in OCs but they were mostly using the e2140's big brother the e2160. Identical CPU but slightly higher multiplier.
I personally used a e2180 for a 3ghz OC and barely touch the voltage which was my goal of getting the highest obtainable clock speed without pushing too much voltage into it. To get any higher I had to bump it up to around 1.4v+ or so compared to the 3ghz OC which was in the 1.1v-1.2v range I can't remember specifically.http://www.tomshardware.com/forum/259899-29-core-overclocking-guidehttp://www.tomshardware.com/forum/259903-29-overclocking-benchmarking-guides
Would still recomend doing further research as well to make sure everything goes smoothly. And so you can fix it if it doesn't. And lastly good luck with your OC.