Hmn... lol.
How about... 435fsb X 8 without any voltage changes?
You just have to try. If it doesn't work, go down until you find a speed that does, then add a little voltage and see if you can get any higher.
Edit: The proper way to do it is to start at stock and increment 5-10 FSB at a time. When you find your limit, try to figure out what component is causing the limit. If it's your CPU, you have a few options.
1: Make the CPU colder. Overclock more.
2: Increase the voltage. Overclock more.
3: Go down a few FSB and accept this as your top speed.
If it's your memory, your options are..
1: Set a memory divider. Overclock more.
2: Relax your memory timings. Overclock more.
3: Replace your memory with higher rated memory. Overclock more.
4: (Only for when you don't plan to overclock your CPU any higher) Lower the FSB slightly and increase your CPU multiplier.
If it's your motherboard, the only two options I can think of are..
1: Check and relax BIOS settings. Overclock more.
2: Get a new motherboard. Overclock more.