Has anyone out there done/found a good cross reference chart for the gas engines we want to convert? You know..like the Kioritz engine is used in Echo brand equipment, and Poulan and Sears/Craftsman chainsaws are basically the same saw...just different name brand.... I have seen reference to the Mustang 50 and Fuji 50?? Just what were most of todays 'model' engines originally used for?