Well, a year later, and I'm finally back at it.
I decided to make an adapter, same as I did on my SJ-2, to accommodate a poly ucup. I had an extra seal laying around that I purchased for the Blackhawk, and the SJ-2 and WS cylinders are about the same ID. The loaded ucup was a little tight in the WS bore, so I took out the "energizer", which gave an acceptable fit. The adapter is threaded 1/2-20 to match the stud on the ram. I gave the threads and the interface between adapter and ram a coating of Loctite 518 to seal against any bypass. Ignore the aluminum washer at the base of the adapter - I was off a little bit when I machined the part, and it was easier to make a spacer, than to make a new part.
I also decided to make an adapter for the pump piston, so I could use an oring and backup, vs. the rare and expensive original piston cup. I turned it out of brass and ended up making the backup ring. It's not that I was averse to spending 10 cents for the backup, but the minimum order at Rocket Seals is $10. And I was able to get the oring at the local hardware for 50 cents. A few minutes on the lathe with a piece of nylon, then I cut a scarf joint with a utility knife. The adapter has a through hole - only because I didn't want to buy a 1/4-28 tap and the drill bit to go along with it. All the threads and interfaces are sealed with 518.
I did end up honing the cylinder - I used a 320 flex hone, which really wasn't aggressive enough, but did clean things up fairly well; hopefully, well enough.
The only other seal that I replaced, was the oring at the base of the cylinder. The cylinder threads, cylinder base, and tank ends all got a coat of 518 on assembly. The hydraulic unit is sitting on the bench now, I haven't filled it yet; if it leaks, it'll probably be from the packing nut. One of the packing seals is in good shape, the other is compromised - it's basically acting as a spacer.
As I mentioned earlier, the drag link studs that join the lift arm to the the short linkages were loose - one was falling out, and the tank was heavily scarred from rubbing against them - clearances in that area are tight. So, I used a dremel to remove the remaining shoulder on the one that was still intact. I drilled and tapped each one to 5/16-18; the plan, is to cut the head off a hardware store bolt, loctite it in as a threaded stud, and use a washer and nylock to secure the whole thing. The force on the drag link stud is mostly side to side and not axial, so I'm fairly confident that it'll hold.
Also, at some point, a previous owner must have gotten frustrated with the push nuts that hold the axle in the yoke of the casters - they welded the ends, to secure them. Not being able to remove the axle, means not being able to clean and grease the caster bearings. I used the dremel with a cutoff wheel to undo the mischief - the picture was taken part way into the process. I decided to take the easy way out - I drilled holes for cotter pins. The bearings and raceways were good enough - the loose raceway had some hairline cracks, but, since they don't seem to be readily available as replacements, they'll have to do. After reassembling, things seem nice and smooth, although I haven't applied any weight to it yet.
Almost forgot - to reassemble the pump piston, I used an automotive spring compressor to hold everything down, while I reinstalled the retaining ring, cutting down the frustration level considerably. I've done this on my SJ-2, trying to compress the spring with one hand, while trying to install the ring with the other, hoping that things don't let loose, putting a dent in my forehead.
I'll report back when I get some fluid in this thing and give it a workout. In the meantime, here's some pictures: