[dsraven]

you gotta look at the whole picture of what you have going on there. does the rad have a straight shot at fresh air or is there an a/c condensor, a power steering cooler, a trans cooler and a grille blocking the flow? next in line is the exit area for the flow. you can't move air through an area that doesn't have an exit. if the rad has ability to get fresh air on the front side but then the rear side is nearly blocked off with engine accy directly behind the rad, there is no shroud around the fan to scavenge as much air from the rad as possible or the engine bay is crammed full of engine with no clear pathway for air flow, then those items should also be looked at.
if you can't find the perfect fan set up you may need to make your own. mock up with craft paper, like cardboard, then when you get it right make it out of sheet stock