Ok, time for a status update on this. I opened up the AC system and my orifice tube was covered in black crap, so that confirms my compressor died the "black death" and most of my system is going to be contaminated. Let that be a lesson not to buy a remanufactured compressor off ebay.
I went to the local salvage yard and found another 98 2.5L ranger with a pristine looking AC system. It still had a bit of pressure in the lines and the insides were all clean and had oil still too. I pulled all of it except the accumulator (compressor, condenser, both lines, evaporator). $45. I vacuum tested all the lines, condenser, and evaporator while I was there with my hand vac pump and tested compressor resistance too. All seemed good. compressor clutch bearing didn't have any play and the clutch engaged strongly when I bench tested it back home.
I bought a can of AC flush and poured it in the replacement lines and condenser, then blew out with compressed air. I ended up deciding to keep my evaporator since it held vacuum and I flushed it too, 3-4 times, to get the black crap out. Bought a new accumulator that came with new seals for the whole system, oil, and orifice tube. My local shop is swamped right now so I'll have to take it to them next week to have the system evacuated, leak tested, and refilled.
I ordered a blend door replacement kit, which came with a new blend door with a metal d-slot top hinge piece, instructions, and metal tape. I also bought a new actuator while I was at it. I cut into the bottom of my plenum and swapped out the door (this was a PITA, freeing the old door from its hinge slots and getting the new door in, there is very little room to navigate and with a pair of vice grips on the old door I was finally able to get it free). The top d-slot of my old blend door was broken in half, so that confirms why I was always getting hot air in the cab. New door and actuator function great and I replaced the plenum piece I cut out and sealed it up with the metal tape.
I also found the source of my vacuum line leak. the gray vacuum line running from behind the glove box to the heater bypass valve on the hoses near the evaporator had a hole it it. The black line running to the bottom of the vacuum reservoir was spliced with a piece of tubing too, which didn't seem to hold vacuum. I swiped all the vacuum hoses and fittings from the donor ranger too so I replaced them and vacuum tested every line with my hand vac pump. all the lines under the hood now hold vacuum, as well as the reservoir ball so hopefully my ac vent controls will function properly now too.
Just waiting to get back into the shop now at this point to evacuate/charge it back up. Fingers crossed.