That all sound and looks very cool, but...

Weight is specified at 7.25 pounds! Even if you can machine that down considerably, you will still be left with a pretty heavy engine.

Power output is said to be 1000 W at 7000 rpm, which will probably give you a workable rpm range of something like 5000 to 6500 and a power output of some 750 or 800 watts... that's about the same as your average .40 glow engine weighing in at 12 ounces...

You will be spinning something like a 16-8 or maybe a 18-8 prop at most...

Pro's: judging by the spec sheet that will be a very long lasting engine (probably a lifetime if maintained correctly), you will be able to muffle that thing until you can't hear it anymore, prop noise at those speeds will also be very low and you can probably fly around an entire afternoon on a 20 oz fuel tank.

Maybe it's ok as a novelty on a WWI triplane...