I like and run a thermal clutch fan. The kind with the little thermostat coil in front of the clutch.

Yes it saves some HP. Also it saves the ears when cruising... a fixed fan can make a noticeable roar. Also it acts as a speed governor for the fan... safe in my experience and others for a ~6,500 RPM redline.

My current fan is a Bouchillon 6 blade with their thermal clutch offering. Works quite well on a warm 496 w. AC. A factory 7 blade with matching clutch should be fine also. Other parts of the package include a HV water pump with anti-cav plate, slightly overdriven fan and water pump and a high capacity 26" aluminum "Muscle Car" radiator from Mancini with matching shroud.