A top view of the compressor and plumbing:
the suction line had another u-bend in it, which I chopped out to use elsewhere. Now the reversing valve is the u-bend.
I crammed the reversing valve in between the compressor and fan motor. The original rig was not insulated one bit, anywhere on the outdoor side. I haven't decided whether or not I will insulate any of this plumbing yet. The reversing valve is a Ranco V3, 2 ton size. It is plumbed for heating mode when inactive. The solenoid coil is not connected to anything yet.
Since the unit held a charge before I got ahold of it, I was not overly concerned with contamination. I pulled a weak vacuum on the thing while reclaiming and filled it to atmosphere with propane. I chopped it open, fitted all the piping, then took the cores out of the service valves. I cracked open the propane bottle slightly, and lit the gas escaping from them. The flame was about the same size as a cigarette lighter. I then brazed the service valve connections and a few more that were not near the reversing valve. I shut off the propane, let the thing cool, and wrapped the reversing valve with rags.
After the whole thing cooled off, I removed the propane source hose from the piercing valve and removed the valve. I connected the propane hose to the service valve in the discharge line, opened up the bottle, and lit the suction line fitting. I brazed up the piercing valve hole with some safety-silv and flux, because the tube was tarnished pretty heavy and sil-fos rod didn't want to stick to it. Most of the rest of the fittings went back together using only sil-fos rod.
After everything was nice and cool again, I put the valve cores back in and connected my gauge set to both access valves. I pulled a vacuum for 15-20 minutes with a really old refrigerator compressor. I shut everything down, closed all the valves and let it sit to see if it had a leak. It held vacuum, so I filled it to about 50 PSI with fresh propane, vacuumed it for another 20 minutes, then charged it with what was left in the propane bottle. If I could find my micron gauge, I would have used it.
I left the unit half-charged and will return to make sure it still has that charge in it later. The unit just started to make frost on the outdoor coil when I ran out of propane, so the reversing valve seems to have survived.
I took more pictures while I was doing work on the unit, but my phone lost a lot of them somehow between when I took them and when I got home. I'll take some more when I go back to check that it holds charge.