If you want a 1:1 ratio, try to go for 7x430. Your ram should work great, I just checked it out on newegg, nice timings. Might want to loosen them just a bit if you go for 850Mhz+. Depending on your cpu cooling, you could go alot higher then 3GHz, around 3.4-3.5 on air.
When stress testing, raise it small intervals, don't jump straight up to the exact overclock you want, ease into it. Check your stability in benchmarks like 3Dmark06 first, to make sure its atleast good for that, then run orthos. repeat this until you reach the clock you want. 3GHz should be no problem. If it becomes unstable, raise the voltage a little. You're correct, you dont really want to go over 60*C, its not the end of the world but not the best practice. Anything over 70 i would consider dangerous. Voltages depend on your cooling once again. I wouldn't go over 1.5v, and really, you shouldn't have to.
Once you reach the final speed you want, stress test it in orthos for an extended period of time. I would recommend trying to find the lowest voltage that clock will run at, not just sticking with the first thing that works.
This is the best I can do to help you out, considering I don't have all my parts for my core 2 system yet. Should be here wednesday though
Best of luck in your overclocking.