Are these the CoreTemp "TJunction" temperatures - one for each core? Or are they the TCASE temperature? If you are reporting an average for core temperatures, that's pretty good. If it's the TCAse temperature, it's about normal. My experience with the E6600, using a ThermalRight Ultra-120-Extreme cooler, was that you would get a TCase of around 52C pushing the processor to 3.3+ Ghz.
Like I said, without "endangering" your processor, you have lots of wiggle-room for VCORE adjustment. I'm guessing -based on experience -- that if you push the VCORE to 1.40V, the load-generated droop in the voltage will bring it back down to 1.37V.
Of course, the trick is to find the lowest voltage for any given over-clock setting. You choose your over-clock limit by attempting to stay within reason given some gut feeling about what might cause long-term damage to the processor.
Look at it this way. Intel sets the retail-box maximum voltage based on their lab tests. Intel doesn't want any processors returned under warranty RMA. Therefore, the probability of damage to the processor at the retail-box maximum voltage is practically 0%. If you exceed that voltage by 0.02, 0.03 or even 0.04V, you're exploring the low tail of a probability distribution for "failure after so many [hours, days, weeks, months, years]." What's 0.04 as a fraction of 1.375V? Less than 3%. Obviously, we don't know what the expected frequency of failure would be, as we follow the linear X-axis from 1.375 to 1.414V. But I doubt that it is significant. And we're talking about failure over some extended period of time. In a way, testing CPUs for reliability is probably not much different than testing light-bulbs at GE.
As I said, 3 Ghz should be easy for an E6600 . . . . 3.2 is still pretty easy. . . ..