I found this PM Research #5 engine in the Baraboo engine show flea market. I got it for about twice the price of the castings. I added the displacement lubricatorand stop valve. The machining was so nice. This is an all aluminum model and now they are brass. Apparently at one time they made an aluminum version.
You probably saw the PM solar engine there as well! I must have gotten there too late to see this one!
Actually,, I didn’t see it. My wife found this one and took a pic of it with her phone and sent it to me. I came right away.