I think the rad mounts was designed with a pedestal in mind or at least for use in push configuration.. if you put the rad on the outside, you are going to go pull config?
There will be a slight performance hit if you go with pull instead of push.. Martin tested this and result is pull only config with no shroud being one of the worst performers, I think next to stacking 2 360 rads together as being the top worst performer..
As with many of the radiators, it's not a perfect squared rectangular shape, if you put it on pull, air flow gets sucked in from the sides between the radiator and the fan spacing, I tested this on a SR1 vs TA120.3 and found that there was a 2-3c difference both using pull only, switched it around to push only and both ended up being about the same with a added benefit of even a lower delta by 1-2c..
Here is the funny thing... that is the testing that convinced me to go pull...
Pull wins at low rpms...