I think there is allot you street considering with one of those calculators.
If you are in a place that evap cooling even works. Dry dry places. Cali, Oregon, Nevada, Arizona, chances are you get allot of sun to.
Solar gain is a real bitch. You can't put your pads on one endwall and exhaust on the other. By the time you get 20 feet down the greenhouse that cool air will be hot again. For pad cooling you have to run pads on one sidewall and exhaust on the other sidewall. That way you are only pulling 20 feet total. You also just effectively lost your roll up sides or drop down curtains. And you have to run about 6 exhaust fans.
Better idea, run real high roll up sides and high pressure misters. The good ones that won't get you wet. Use good horizontal air movement fans to get that water evaporating over head.
Exhaust fans for me are just during black out or on coolish days. On hot days my sides are open.
As far as good fans go, everyone makes them. Are you running light traps? That will dictate what kind of fan you need. The housing type will make more of a difference then brand. You can also get housings/shutters separate from fans
Schafer, dayton, valuetek, whatever.
You also need to decide if you want Belt driven or direct drive.