The Mira is not an issue because the
control board for the AC unit (silver box where all the wiring connects near the front of the AC unit) is typically not replaced with the AC unit making the swap fairly quick and easy.
If for some reason you did replace the control board you would need to open it up and set the dip switches to match your old one.
Make sure the new unit has a
gasket on the bottom between the supply and return, when I replaced mine that gasket was not included. You can remove it from your old one.