Speeding up the flow, if the rad can't keep up, eventually it's going to overheat. Slowing down the flow, if the engine is heating faster than dissipation, it's going to overheat.
Huh? If a radiator can’t keep up? Have you any experience with such a scenario? I do. Undersized radiator for the application is more fitting.
Then you want as much air flow unimpeded: no flat shroud and/or electric fan that has a bulky blade blocking air flow, a good mechanical fan, (fixed or viscous) as big as you can fit, a high flow thermostat (I run a disc akin to a gutted 160° no bypass hose etc) and high flow/volume pump. No slowing down anything.
I have vast experience with what it takes to make a stroker (not to mention other Mopars through the years) with an undersized radiator (18”x18”) in an oppressive compact engine bay with less than ideal frontal air intake run cool trust me.
