Well after seeing those other pics, I think my guess is correct. This was in the nose of a scale model of some sort and was to represent a LeRone rotary engine like was used in WW-1 plane such as the Nieuports 17, and 28. These were rotary engines, where the whole engine rotated and the prop was attached to the crank case. No way to do that at this time with a model engine! The number of cylinders may just be a factor in that he bought all the Williams Brothers cylinder kits that the hobby shop had! If it was a Nieuport 28m it had a full cowling that would hide most of what you see. The earlier Nieuports had an opening at the bottom so that the castor oil used to lubricate the valves from a total loss type system would not collect at the bottom as it was slung off the cylinders, and then tend to catch fire. The type of engine in this would help date when it was made. I'm guessing in the 50's. A lot of work went into this. It wouldn't be too bad just to display is I had the disposable funds for it.
Type at you later,
Dan McEntee
Edit to add: In looking closer, it even had a butterfly type restrictor throttle! It all looks home made but very well done. The more I look at it the more I'm impressed when you consider the time period it was made in.