xringer,
I did the same thing with my other vintage window rattler! It's a 9000 btu kenmore, pretty much a clone of the one in this project. It's proving its right to live in the sunroom window as we speak. I basically just reversed the connections to the compressor (the pipes fit inside each other when spliced), brazed a service valve to the factory crimp jobbie (bullet piercing valves are ok to suck out the cfc refrigerant but that's about it), and left the rest alone. Vacuum, purge, vacuum, purge, vacuum, refill w/ propane, run. As for the control, it has a bulb thermostat which has both no/nc contacts. So now the factory thermostat heats!
Thanks Sears... they must have made 25 models out of this one frame... I did have to move the sensor bulb off the coil so it cycled less often. I imagine the original model had a strip heater someplace when equipped