Big Block Fan

Your radiators are too thick. Get t three row brass copper, or a two row aluminum and it will be plenty. Your problem isn't radiator. It's air flow. If you get a thinner core, you'll have the room you need for a clutch fan unit. That will solve the idle over heating issues, I believe.
mine aint too thick , its a 2row , w/ 1 1/4" tubes.