Have a look at Gigabyte DS4 or DS6. The rev2.0 versions have quad core enhancements and these boards are superb overclockers. See below for my clocks - tho I only have Core2 Duo.
Your main issue overclocking a Quad won't really be the motherboard, there are plenty that will do a good job for you (Asus and Evga also have some very good models to name a few), your big issue will be cooling as the Quads generate a lot more heat than Duo's, and you will need to look at a very top end air cooler or better still a water cooler to keep the thing cool. If u re feeling wealthy, a nice Vapochill or nVentivePhase Change cooler rig would be nice.