Honda makes tillers and also sells loose engines to other companies who mount them on their tiller chassis. I think you may have a Honda G300 engine on <somebody else's> tiller chassis? All, 100% Honda tiller models start with an "F" model name...
If it's just a Honda G300 engine, then yes, Honda does offer a full 74-page shop manual for that engine in paper form only. It includes lots of details on both the breaker-style and CDI ignition systems.
For example, on the CDI type, the resistance between the RED and BLACK leads on the exciter coil should be 240 ohms, and infinity between engine ground and each lead. Note: Some G300 engines came with a coil for charging a battery or running a light circuit; in those engines, the resistance between the BLUE and BLACK leads should be 1400 ohms.
You can get one here:
Honda Power Equipment Shop Manuals on eBay
-Robert@Honda
Caveat: I work for Honda, but the preceding was my opinion alone.
