I had an OS FS-120SII I was going to run with ignition and gasoline. I found a suitable Walbro carb, but it needed a few parts to mount to the engine. Details can be found here OS FS-120SII Gas Glow Conversion. There is also a video of machining one of the parts required on a small Emco vertical machining center PC Mill 125.
The engine does run with this carb and the OS G5 glow plug, but requires plug heat to run well. Increasing compression ratio should improve running.
Finally, within a week there will be closure to the Enya 41-4C disassembly video, but it won’t be as expected.