We need to rule out another variable, and the biggest one it seems now is the 132 as most suspect.
I may attempt obtaining 152 to dust off the truck this evening. Any brand preference? I am concerned about not being able to find a can piercer locally to assist in the 'cleaning' of my truck.
For the most part you have eliminated my biggest suspects. Assuming you have pinched off the heater hose at the hot water outlet on the back of the engine.
What I get out of your testing.
Compressor is capable of pumping.
Rear expansion valve makes little difference pinching the high side line so it is not flowing excessively.
Front orifice tube is flowing given the high low side pressure readings and the fact it behave the same with a fairly clean stock orifice in place.
Also assuming you have done the condenser mist test to verify it is cooling adequately.
The charge has been altered up and down with no huge gains.
To me that leaves one variable, the refrigerant gas. In two completely different systems it is showing fairly suspect results.
The dusting should give us a controlled expirement. I would start with 30 oz monitoring pressures and temperarures and work up from there.