As I stated in my write up most engine builders would agree that the intake opening point and exhaust closing point are the most important factors in valve timing. I have not tried to make science out of the crank gear positioning. One would assume there is a jig but maybe they just slap them on? None including the original Listers had a key that I am aware of. Like everyone else I get a bit smarter with each one of the Indian engines that passes under my fingers, but so far I have found that bent camshafts, not placement of the gear or lobes is the primary reason for timing deficiencies. One has to play with a degree wheel and indicator to realize how much a slightly bent camshaft affects valve timing.