A 252CFM fan paired with 50CFM fans will behave just like the 252CFM fan...or within like 1-2%. There might be some weird noise though.

I don't understand what's bad with push/pull either? Every test I've ever done (both anecdotal and published) shows a nice increase in airflow with matched and nearly-matched fans for not much more noise

Other than that....why on God's green earth would you use 3 MONSTER fans?! I don't think you understand the type of noise that will come from those fans. Your neighbors might even hear them. You won't be able to hold a conversation in your room. You probably couldn't even hold a shouting match in your room. :-/

They're GREAT air movers and very well built. But they simply are not acoustically economical. Heck, they don't even undervolt well (on a rheobus, big ing variable resistor (BFVR), regular BFR, or really any other method of fan control) either so forget about lowering their RPM to control the noise. That massive amount of airflow isn't particularly necessary either. Nor is a PA rad a good use of that much airflow.

Find some nice ~1600RPM fans and you'll be only a few degrees off and your room will have a nice, mostly-quiet hum coming from a high-performing beast of a computer. Or if you want LED fans...do push/pull with LEDs on both sides of the rad