I saw Nick Muller's 3 cylinder radial engine several weeks ago on another forum and asked him if he would be willing to sell me one of the castings. He graciously agreed to and yesterday the casting arrived via US Mail. There was no glaring evidence that the package had been opened by customs and, so far at least, no invoice from the Post Office or Customs Office for any fees or duties.
The casting was nicely done although it did require some cleanup with a file to remove flashing and smooth some of the edges. Here is a photo of the casting mounted over the 3" 3-jaw chuck on my 7" minilathe.

Not the best work-holding method, but by taking light cuts and slow feeds, I was able to face off and turn down the outer end. I also drilled out the center hole for the crankshaft, starting with 1/8", followed by 5/32", and finishing up with 3/16".
I plan to mostly follow Nick's plans but want to incorporate my slave exhaust valve in the head, so the top end will be quite different. My head design won't be quite as nice looking as Nick's, but I can't use my slave valve with his design... bummer.
Chuck