I yanked a big electric fan off a mid 90's T-Bird. I've got a high compression 327 and that fan combined with an aluminum radiator cools it just fine (even when I lived in Phoenix). The fan is two speed. I have the high speed connected to a relay, operated by a thermal switch in the intake manifold. The low speed is connected to a 3 way toggle switch. Power will only make it to the high speed circuit if the toggle switch is in the off position.