On pages 44 & 45 in the Jan 2016 Hemmings Henry's first engine is featured.
One of the stationary engine groups there were plans availible to biuld one
Brent Mize, a terrific coil rebuilder, had one built and runs it at his spot at Hershey. It was shown in an earlier thread but I did a search on the board and couldn't find it.
There's many variations of the engine on YouTube. The Penn State version uses what looks like a Briggs & Stratton lawnmower cam.