Yes, I will have separate metering devices for heating vs. cooling. I may use two txv's in this one, or I might keep the cap tube for cooling and for a method of easily charging the unit. The unit will essentially function as a larger R22 type split heat pump with the Hx in the suction accumulator.
This guy calls it a liquid suction heat interchanger, why I don't know.
Liquid-suction heat interchanger
The main purpose of the exchanger will be as an accumulator. With the unit I have now, I can only push the superheat down to about 15 deg F before the evap starts burping foam. It seems that oil dissolves really well in R290. With nearly no distance between the evap and the cxr, the foam was going straight to the pot.
The pros all told me that this always happens with room ac units if the superheat at the cxr inlet goes below 30 deg F. BTW, I find that the forum experts will tell you anything you want to know if you stay IN THE BOX. This includes making up a story about a generic something you are working on somewhere. It also means talking in their language. In your case, I would reference the westinghouse unit at a brokedown palace. Homeowner Joe Dirt inherited the place and can't afford a new unit. Only then will the experts bare their souls on your problem.