talk to the experts on tech line at VINTAGE AIR, or talk to the DERALE fan people. They sell both types.
Electric fans have armatures and bearings, both fail. Steel or aluminum big pitch solid fans only thing goes wrong is belts.
If running air, your also trying to pull thru another radiator and that will cut down the air flow and make it much harder to cool. The addition of a shroud will help immensely .
mike