If you are using an external governor, the headspeed can be displayed of course. Therefore you will need a phase- or other rpm signal (external phase or magnet sensor) and the correct settings for the sensor and the gear ratio.
The values will be the same as on a model with VBar Governor and are explained in the manuals—see basic setup for non-Mikado models.
Note This App needs only to be installed during setup. It is not necessary for the operation of the model.