Please explain me why you wanne do that. With three screens you configure DCS with three screens.
Then, if your model has a 140 FoV limit, you will have a max FoV of 3x140=420 degrees. But you wont be able to place the monitors correctly. I can garentee you that 3x120=360 is more then enough. But then you would have to place your monitors in a triangle and stick your head between them from below or above... This is possible with beamers in a big room though. And with beamers you need some overlap for blending the views, so 3x140 might come in handy.
I find 3x60=180 more then enough sitting in between the ends of my side monitors in a 60*/60*/60* placement for a full 180 degrees view.
*=Degrees