4ghz is a bit optimistic. You might get lucky for benching but you're not going to get 4ghz or higher stable on an E6600.
That said, about 3.6-3.8ghz can be expected with a good stepping and watercooling...after that the vcore requirements are insane. The only 65nm chips that hit 4ghz somewhat consistently were the E6750 and E6850, and even then more often than not you could not do it.
80 for a maximus formula is not bad at all though and should get you a decent clock with the e6600....i used to have a P5E with a rampage bios and that board was pretty sweet and got me great clocks on all sorts of chips.