OK had a chance to do a little more research. There are various versions of this board but its possible that it takes the 240v AC and rectifies this to provide the DC for the spindle so be careful how you relocate this into the new box as there could be 340v DC on that board.

Personally I'd get a new 36v power supply for the steppers as the new drivers can handle it and you'd get speed/torque benefits.