That's a Northwood C chip, so you should be okay. But I'm not crazy about running any P4 above 1.7 vcore.
How much do you lose turning down the juice? If you can run 265FSB and get the vcore under 1.7, you'd still be running at 3.18GHz. Might not be a bad insurance policy.
BHD
(edit because I had a brainfart and originally typed Northwood A.)
as long as you have good air flow though your case, that heatsink should be fine with 1.7V. But just as it was said above, taking it down would be a good insurance policy.
also, some chips need more juice than others; if you were to have only default voltage on that chip, you prolly would go very high(i am assuming you didnt start at 1.7V )