For that information, your best bet would be to search forums - see what others with similar set-ups are getting and using. Find an overclock that isn't too aggressive, see if you can match it. If you can with stability, you can use that as a base to start your small steps upward. If you can't match it with stability, look for less aggressive numbers to work from.
I've not clocked any IB processors so I couldn't say what a good baseline number would be.
Keep in mind that even with exact same equipment, the variables are such that no two CPU's will clock identically (at least the likelyhood is low) which is why you don't find specific numbers...
define stability, do I run the system and see if it crashes from cpu heat? how can I tell if it's unstable? I understand that there are some other factors, such as temps outside the case or some tiny difference between 2 of the same cpu. I just wanted to see if I could just put in some "moderate" overclocking numbers and have it work faster without really pushing the heat limit.
Stolen from Wikipedia "Overclocking" article
"In overclocking circles, "stress tests" or "torture tests" are used to check for correct operation of a component. These workloads are selected as they put a very high load on the component of interest (e.g. a graphically intensive application for testing video cards, or different math-intensive applications for testing general CPUs). Popular stress tests include Prime95, Everest, Superpi, OCCT, IntelBurnTest/Linpack/LinX, SiSoftware Sandra, BOINC, Intel Thermal Analysis Tool and Memtest86. The hope is that any functional-correctness issues with the overclocked component will show up during these tests, and if no errors are detected during the test, the component is then deemed "stable". Since fault coverage is important in stability testing, the tests are often run for long periods of time, hours or even days. An overclocked computer is sometimes described using the number of hours and the stability program used, such as "prime 12 hours stable"."
found here http://en.wikipedia.org/wiki/Overclocking