Your pressures were so high, that I expect it was overcharged with 134 added to the 12. The idiots that do these things should be hauled off and castrated.
Just for your future reference, when an expansion valve is stuck or the system is otherwise fully restricted BOTH high and low sides go down, with the low usually going to a vacuum.
To get this thing right you need to break all connections and flush thoroughly to remove all the old oil. Replace the o-rings and use nylog to help them seal. Remove the compressor and flush it out several times with mineral oil, don't use solvent in the compressor. Make sure you blow ALL the flush agent out of the individual components.
Put in the specified amount of mineral oil and it doesn't hurt to put a little in the evap, some more in the condensor and a little in the compressor to total the volume needed.
Last thing before closing it up put in a new receiver dryer. Evacuate the system thoroughly and charge with R12.
You shouldn't have to purchase anything but o-rings, nylog, flush gun, flush agent and receiver dryer and R12.
Once you're done, feel proud of yourself for saving another good a/c system from one of these knuckleheads that will put anything in the system and not care about the consequences.