To clarify my comments, an electric fan can be a Puller or a Pusher regardless of whether its in front of or behind the radiator. Just a simple matter of switching the POS/NEG wires.
The point is that the air flow SHOULD normally flow from front of grill and through the radiator toward the engine.
Thus, an electric fan mounted in front of the radiator should PUSH cool air into the radiator. An electric fan mounted behind the radiator (where engine-driven fan was) should be PULLING the air into the engine compartment.
To set it up otherwise is completely counterproduction to basic forward motion and normal airflow. Use a lit cigarette or other smoke stick and hold it in front of the grill, that'll show you where the airflow is going. A good, well-sealed electrical fan will suck that smoke right through the grill and into the radiator. Bingo!!!
'68 428 HO M3 Monster, 4-on-the-floor! Need I say more?