Do you have an overheating problem, or are you just anticipating one? Cowling around the fan helps push or pull more air through. A chin spoiler creates a low pressure area behind it, which is below and behind the radiator, and pulls air away from the back of the rad.
Retarding the advance a couple of degrees may also help.
When these engines get hot, it helps to run the heater because the heater core is a small radiator. "Water wetter" claims to help, but maybe you hae a radiator that has some of its core, clogged up, so flush it. If yor drive in a hot climate, consider going to an aluminum radiator, they are available at racing dealers.
A raised lip in front of the louvers will also create a low pressure area behind it,drawing air from the engine compartment.