Heater Demister FRUSTRATION!!!

The car is 73 . This is evident in the presence of 2 NOX valves on the firewall.
It appears the heater case was changed to pre 73. This would explain the fillers in the firewall at fan and tubes. My guess is someone did that in order to add a/c to a car that didn't have a/c. If that is in fact a pre 73 HVAC you do have the correct controller for it. How to mount it in a 73 dash ? I don't know