Are you mounting these as a vertical stack as per your sketch? If so you want the fans blowing the other way. I have fan-shroud-pa120.3-shroud-fan on top of my case and the heightof that sandwich is 168mm, not including the 40mm standoffs which support it. If you add two more layers then just the sandwich will be 464mm tall, +40mm if mounting on top of case (would not be safe on top of case if you ask me). I guess you will be making a rad box, or standing them next to your case.
However, if you are going to the trouble of making a rad box then the overall cooling potential will be noticeably better if you don't sandwich any of the rads together and treat them separately, even if you keep the same number of fans in total. Tests with sandwiches have been done over the years and it has largely been proven that independant rads cool better than sandwiched. With three rads together you may actually stall the fans due to the static pressure required to even get a unit of air through the sandwich, unless you use high static pressure, i.e. noisy, fans.
With that many rads you may even find if you mount them in a horizontal fashion, and not stacked, that you could even get away with no fans at all, or very low speed fans at any rate.