Thanks for the video and keeping up to date. hahaa...next time hold your phone horizontally though
That looks to be about the same as my gas powered Honda 5hp 4 stroke power and speed wise, which is good considering propane is technically a less energy dense fuel.
I looked into a propane conversion but there aren't really any off the shelf options. The only real thing I've seen people do is plumb a line off a propane tank, take the fuel bowl off and stick a hose on the fuel jet. It seemed pretty sketchy since you can hear the propane flowing out of the intake of the carburetor but it did run on it. I'm willing to bet that you could buy a Lehr carburetor and make an adapter plate and it would work fine on another manufacturers motor or possibly find another propane carb from another application and do the same.