Are you going for the water cooled or air cooled version? Hit and miss? The Upshur horizontal farm engine was my first I.C. engine (and second ever engine). While I did get it to run, I never finished it off. I'll have to revisit it sometime and give it the finish it deserves.
I finished the cylinder with the cooling fins, I'm always scared when I work with the cutting tool, sometimes the chip fits between the piece and the tool and it's a DISASTER ! In a photo of the cylinder you can see a thin edge, in the cooling group I made a furrow so that the cylinder can no longer move