I've been using Derale lately (dual w shroud), work good, but still a little on the low cfm side. I think they are 4000cfm max, together, can find others that work well. They are pretty flat too, and dual fans offset the motors so no interference with the water pump snout.
Thing with high cfm fans, with no soft-start, they pound your alt and wiring, and you have to do something for hot re-starts, they can drain starter power if they come on with the key. (controller)
If it's a track car, you can just do an on/off switch, but still have to remember to turn them on or off, to avoid those oh-chit moments.
PWM controllers are the way to go, and you can have them not come on until a certain RPM is reached, like 600 RPM. Some controllers are not potted, and can't handle weather, not sure what good those are, but many never check to see if they are potted.
I suggest deep cycle batteries when using E-fans too, obvious reasons.
Spal hands-down are the best. They advertise 'primary cooling' functionality, something many fail to address. You do pay for the premium tho.
I'm sure many OE fans work, but if you want to be sure you have ample flow, source them from trucks.
CFM ratings are not standardized, but usually amp draw is a good indicator. For dual fans, pick ones that are 25a or better.
This is the Derale setup I use on my 68-72 A-bodies:
https://derale.com/product-footer/el...s/16837-detail
I know people that are using the Derale PWM controller with good results, they at least last a few years. You get a slight deal on pricing if you buy the 'kit' with the controller:
https://derale.com/product-footer/el...s/66837-detail
You can have one or both run at a lower % starting around 150 degrees, and ramp them up to 100% at like 190-195. They have delay & soft start and a 20-sec after shutdown run feature.
Shrouds have relief vents too, many overlook that feature.
.