I took the picture in 1958, so it's the last development of the Kuchen engine.
A wonderful cutaway drawing exists, the work of my friend Tom Fornander. He did it from the drawings of the engine given me by Richard Kuchen. They are now in the REVS collection in Naples, Florida.
The project launched Fornander on a career of decades making cutaways and technical drawings.
This and 49 other engines are in my book "Classic Racing Engines". I'm surprised it's not referenced much here.