I also want to add to what Dave said here, yes cranks can be bent to clear the pull starter/recoil starter as I grew up calling it..LOL
I ran one for a while on one of my engines and the way I avoided needing to modify or change cranks was that I just mounted the engine higher in the frame, I mounted engine in frame with rear mount only after raising it just above the crank, then I built my front mount so that it extended to front down tube, this can be done with a piece of flat strap steel that has holes drilled so it will attach to engine and then bent so that it extends down to frame tube, then another bend so that a U-clamp/muffler clamp can be used to secure the mount to the frame.
Some frames wont allow the engine to be raised enough and I'm not sure if yours will or not, but if you really want the pull starter on the engine that may be an option that will get it done for you, but if it wont work and you decide to go without it, bump starting the engine like most of us do wont hurt a thing as long as the bike is set up right and all things are nice and secure.
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