What is the story on the .29? I do not recall ever seeing them advertised or listed in the Fox catalogue. The .36 also was available in a throttle model for Carrier but I think the rules for that event was also changed to permit BB engines. No wonder Duke was upset at the AMA!
I think Duke had other problems about that time.
The 29 was definitely advertised, and I knew several people who had them in the era. It was a decent performer at the time, slightly more powerful than a OS-25S and less than a OS-35S, nothing to write home about but satisfactory. They had the same issues of the other Fox engines at the time, sometimes requiring a cleanout and frequently required lapping the piston followed be very extensive break-in to get it safe to fly with.