[clay68c10]

You already own the fans that are on it, give them a shot. If they work, then set up a more elaborate trigger to switch them on.
If they don't work, then go mechanical or hi-capacity electric.

That said, I ran a Lincoln MK8 fan on a 454 w/ac when I lived in TX. Even in stop and go DFW traffic with the air blasting, the eng temp never went over 205. A properly set up e-fan on a 4-core radiator will keep it cool.