I respray the radiator black again occassionally from the front to add a protective layer and slow down the corrosion.
Also been thinking of insulating the radiator from its support with rubber spacers and nylon washers under the boltheads.

I used to run plain tap-water with the 318 in the car because the engineblock would lose about 1 liter per week, but now I'm running normal green coolant again with the 360. Not sure if that would help/solve anything 'electrically or galvanic' for the radiator as the corrosion is on the outside.