It appears that you will have about 1100 cfm capacity if you are using the 115923 motors. SF 1020 has 12 motors, SF 1200 has 16 Motors.
You also should have the ability to read very accurate flows anywhere
in that range with the three Pitot tube array.
I am not sure how you are doing the suck vs blow valving in your design
but assume that when the valve is in one position the center chamber
feeds the motor arrays and the exhaust from the motors goes somewhere.
Same deal for the Exhaust testing.
I have seen the rotary valve work with a two chamber box but not a three chamber box.
More info please.
Tom V.