Could be worth a look. Some General Supply/Hesse history.

https://muskegon.craigslist.org/hvo/d/vintage-willys-air-compressor/6551939433.html

“This is a Willy’s Go Devil engine. This is an engine that has a conversion kit on it to make it into an air compressor. The engine is stuck, not blown up! The generator is missing also the air tank, air gauge, and fuel tank. I put some trans fluid in all of the cylinders about five months ago. The block is not cracked! It was built between 1945-1955. If you are restoring a Willy’s Jeep and need a engine this would work well for that.
I just don’t have the time to work on it right now, so I would rather re-home it than let it sit and collect dust any longer.”