He posted today with 3 pics, it's the last pic. There is a significant amount of open space on the radiator that the fan doesn't draw air from, probably half the radiator. That's fine with road speed or a lower output engine, not a 408.
A shroud is important to fully cool all the rows fins. I don't know of any oem vehicle with an electric fan that doesn't use some type of shroud. But Im sure there may be a few.
If you have an electric fan with a shroud and it is causing a restriction at higher road speed, then you simply don't have a large enough fan with enough power/pitch in the first place.