I made good progress on the wiring: the front is completed, and the power has been connected to the back.

As you can see in the pictures below, the voltage of the two power supplies are displayed on one panel and the lever allows to switch between the two while a potentiometer allows to adjust the voltage of the one for the spindle/laser.

The power supply for the motor is not meant to change and while it can be adjusted it is not necessary to have an easy access to do it.