Hi Daniel, a big CONGRATS on a fine acquisition for your collection.
Perhaps a bit of timing will help. 60 to 80 psi ought to be downright scary on one of these without a work load and without a governor.
Well the video the seller had of it running did show it "jumping around" pretty badly, but I think that was mostly due to the wobbly table he had it set up on. Even though he said his compressor was giving him 60-80 psi, I doubt that the engine was actually seeing that much, as it would also depend on the volume of air, and not just the pressure of that air, that was making it into the engine. With that said, I will add that much of what I have found so far would definitely preclude this engine running on any "reasonable" amount of air or steam. Large volume and substantial pressure is the only way this engine is likely to turn over in it's current condition, as you will soon see with further postings.
Certainly my little airbrush compressor at 25 psi would not budge this big brute, even though I believe the pressure should have proven adequate (just), but the volume was lacking. I couldn't even get the D-valve to seat, so all the air I was putting in was just blowing out the exhaust!
Most, if not all of the issues with this engine will be revealed in due course .... so stay tuned!