C90 electric start engine

I just acquired an early ST50 Dax. It needs a lot of work, parts missing etc. It has come with a 6v C90 engine (good) in the frame and two electric start engines in a box! There is also a loom and switch gear with the engines. Early observations note that the intake for the carb on the electric starts are pointing in the opposite direction. I cannot find an image on the web of a Dax converted with this engine, has anyone done it? Pros and cons?