That would be the tightest timings but only BH-5's will do that for the most part, that or underclocked RAM like I guess you're going to have it, but you'd probably still need a little extra voltage for that and even then I don't know if it'd do it.
What's the stock timings for that RAM? if it's something like 3-3-3-8 then since you aren't underclocking it THAT much I'd say 2.5-3-3-7 is safe and that's not even really worth changing it to as it's not a huge performance difference.
2-2-2-6 might be feasible with more voltage though, but if it's valueRAM it might fry under the voltage.
My mobo supports up to DDR333 (PC2600)
Sure that's a typo, but yeah you mean PC2700