we did fan/ radiator testing for Ma Mopar 40-50 years ago on the famous BAker Grade (Death Valley turn off area) 5-7 miles upgrade

You really need the fan clutch and 7 bladed fan- 9 bladed on reverse direction serpentine like my Magnum
Mopar speced different temp cut ins for different vehicles
The late one I remember we went from a 185 degree 7 blade 3" pitch to a 195 9 blade 2 1/2 inch pitch (serpentine)
Worst case was stop and go up hill in heavy traffic WITH A TAILWIND
we found the air would recirculate through the radiator then get blown back in front of the car or truck and go around again
MOPAR changed the Valance/ spoiler designs
Worst case around town is stop and go with the AC on
The output of the AC goes way up with a flex fan or a 5 blade steel fan
this is also where an electric pusher is helpful
Put your shop fan in front of the radiator on the dyno or not and turn the AC on with a temp guage/ probe turn then fan on- see/ feel the difference
so- plug all the holes in the core support
add at least a factory valance
run the clutch fan with the appropriate fan for your radiator/ shroud
do run a shroud with the fan in the proper place in the shroud
The hardest thing is getting the hot air out of the engine compartment
coated headers/ exhausst really helps
the valance creates pressure in front of the radiator and low pressure behind the radiator and prevents the tailwind problem
BTW I have a switch in the spedo drive that - thorough a relay- turns off the electric fan around 28mph another relay turns it on when the AC head pressure goes up under 28 mph (most of the time keeps the noisy fan clutch fan from coming on-- the 7 blade is noiser than the 9 blade
GM is using an 11 blade I'm going to try
hope this helps
do you run a selonid that bosts idle when ac is on?
water pump with solid or plated stamped impeller helps
18 pound cap and good hoses