Wow, this is getting dicey. IMHO, and I speak from experience...(dual) pullers is the ONLY way to go...bar none. And yes the incoming air has already passed through the heat exchanger.
With a pusher you might as well place a piece of cardboard is front of the rad. Same difference.
Go back and take another round of measurements...with dual fans most of the time you can achieve a tighter yet acceptable clearance.
