Why not just raise the idle speed a couple hundred RPM? You'll spin the pump and fan faster and also sling more oil up onto the cam. If you are heating up at idle you probably have an airflow issue more than coolant flow.
Personal preference, I guess. I'd rather overdrive the pump and fan slightly than raise the idle to 1000 rpm. The car doesn't have an overheating issue. The temp just creeps a little more than I'm comfortable with at stop lights. Raising RPMs with my foot brings it right back down. Pretty sure the right pulleys would work great. Another option is finding a fan with more pitch.