73 Dodge Dart heat control

It's been a while.... anyway the Dart is back from the rewire. A few issues with that but I'll work through it. Fi Tech system fitted... don't know how well that works came back with zero fuel in it... ten mile road test my ***... the new gauge cluster is showing 3 miles...
I degrees the heater/ac system was beyond trying to fix/source parts etc. There was no chance on my own figuring it out. The question I pose is. Has anyone fitted a heater assembly from another car into one ? I not bothered about A/C aslong as I can control the heat and direct it.