[ByronRACE]

Even with the twin pushers on mine, turned off, moving down the road is enough airflow. That's with no shrouding in front of the radiator; just the body opening and air is free to bypass the radiator and flow all around it. It's still enough.

I can't imagine the single puller being more restrictive. If you like the shroud and mechanical puller, that should be plenty...especially if there's no fan clutch. It should be overkill if the shroud is designed right with no leak paths and the fan positioned at the right depth at the outlet so the fan is efficient. Even at idle when you're not moving, that should be plenty. If you have any leak paths where the fan is moving air that did not first flow through the radiator, the air will favor that path...especially at idle. Even a small 1/2" gap all the way around where the shroud meets the radiator will make a significant difference. The total area of a gap that large provides a less restrictive path than the radiator. If you look at OEM radiator and shroud designs, there's all sorts of seals and bits of plastic placed here and there to channel the air through the radiator instead of around it and to prevent hot-side air from recirculating around to the cold side and being sucked through the radiator again when the vehicle is stationary at idle.

My dad split the fan shroud on his E150 to make it easier to work on. The result of this created a 3/8" gap in the middle of the shroud on both sides, and about a 1/4" gap between the radiator and the shroud on the top half of the shroud. At idle, it would overheat. I duct taped up the fan shroud to experiment and it solved the problem. Ended up having to buy a new OEM shroud. The small stuff matters.