Olson’s V8s specialize in building motorcycles powered by Ford flathead V8s but this particular model is powered by a Lincoln-Zephyr flathead V12. I do not know which version is being used on this bike but the V12 came in three sizes 267, 292, and 306 cubic-inches and had about 110 horsepower and 180 ft-lb of torque. These were similar to the Ford flathead V8s except they were a 75° angle V instead of a 90°.
Source: Olson’s V8s via OppositeLock