Ok went out a and did a little checking and blew my theory out of the water,the lightening hole drilled in the last throw is not centered in the rod journal so will have no effect on the depth of the half moon,also took calipers to a 64 352 crank an C1AE-A 390 crank and the half moons appear to be identical in depth,so looked at a 428 crank and noted that it has a notch and a drilled hole in the flange,then looked at a later 2U 390 crank and guess what, it also has a notch and a drilled hole,so based on that I don't see how the appearance of the crank flange can be of any help in identifying the stroke of a crank like chevrolets.It appears that most earlier cranks used the half moon and notch ,while some later cranks used a drilled hole and notch,it does appear that some of the later 360 2T cranks still used the half moon.So lacking the ability to turn the engine over and measure the stroke ,your stuck pulling the pan unless you have a borescope that you can stick in the drainplug to check the counterweights for bevels and all that does is eliminate the 3.5 stroke crank,it could still be either a 3.78 or 3.98 stroke crank.This of course only applies to stock cast FE cranks,forged 427 or FT cranks are another matter.