A couple of lessons from my own experience:

1) Distilled water and a bottle of water wetter will keep the temperature lower than a 50/50 mix of green antifreeze/coolant. The antifreeze holds (retains) more heat than straight water. Straight water cools quicker than ethylene glycol (mixed with water or unmixed).

2) In the middle of Superbird production (late 1969), the factory engineers changed (on 440 motors) from a clutched fan to a direct-drive fan (no clutch) due to Bird cooling issues at "highway speeds". Thus, a direct drive fan helps pull air through a radiator better than a clutched fan - shroud or no shroud - at highway speeds.

3) When you have the money available to buy that Glen Ray Radiator...DO IT. Using a 26" Glen Ray Radiator, and distilled water and a bottle of water wetter...I had to "work" to get the temp up to 180 degrees on my Super Bee. Glen Ray builds a helluva radiator.