It looks very simular to my first router, i reckon you should beef up the gantry some more,run something across the back of the y axis plate and swap the z axis rail and bearing blocks around so the rail is on the back of the front plate,
not sure what zapps high voltage kit consists of as ive not been on there a while.but on both machines i knocked up ive used zapps pm752 drivers and their SY60 steppers,cant fault them.