After 2 rows in a radiator, the cooling effect is much diminished. A third row does NOT increase the cooling by 50% over a 2 row. Also you need to check fan clearance.
The real issue with 3 and 4 row radiators is with out the fan shroud; a open fan cannot pull enough air flow on its own. The air it grabs is from the edge of the fan and it by passes the radiator all together.
If you use an open fan- go with a long tube radiator and 2 cores if available. Long tubes are wider than the standard radiator and give larger cooling area to dissipate heat or just use a fan shroud. An electric push fan on the front helps a lot at stop lights and the cars movement forward pushes the air thru while driving.
Hope that makes sense to you.
Joe