To close out this thread, here's the Rest of the Story...
Sent the pump to thepumpguysc, who had a devil of a time finding parts as well. His overseas supplier sold him the barrels and plungers needed, then cancelled and refunded the order without explanation. He searched for other suppliers, but to no avail. In the end, he ended up replacing all the seals that he could still source, went through the pump for me, and sent it back.
I reinstalled the pump (which was MUCH easier than expected since I now knew how to take things apart), changing out seals, gaskets, and o-rings for other parts as I went. Once assembled, I primed the system and started it up. Ran great and no longer appears to be 'making oil.'
This journey showed me the disadvantages to owning a 'rare' tractor, but I'm glad I stuck with it. I learned a lot about the engine and other systems as I went. It was frustrating at times, but the results were worth it.
For anyone else in a similar pickle, the only matching pump I found on the web was one at Spencer Diesel in Iowa. They want $1,500 for it (plus a $300 core charge), but it might get someone up and running.