It may make a difference if your 450 has the serial port option or not.
I have a cruizer II and an old 450 without the serial port.  I feed a wire from my center boom valve back to the remote sense wire on the cruizer II to let the cruizer know when the sprayer is on.  This works fine except when I shut off other parts of the boom and the cruizer only knows "on" or "off" for the whole sprayer width based on the center boom section.

Sorry, I have not tried to get a speed signal out of the cruizer yet as my old radar still works on the scs450.