Do you know if that engine is the same design as the 50? I've got a couple of pictures from when I put the big bore kit into my 50 I could post if they are.
Line up the marks as shown on both the crank (flywheel) and the cam chainwheel. The cam lobes will not be depressing the valves, rather, they will be off the valve stems, pointing away from them to some degree (not sure to what degree, however, but it's hard to mess this up). Good luck!