I measured the thrust surface on a couple of my "440" cranks. Both were ground to use in the 400 block, and one was offset ground for more stroke. One of them had a thrust surface large enough to cover the large 400 bearing, the other didn't. As I recall, one side of the thrust was bigger than the other too. Remember, the 440s changed thrust bearing size too, but most of the "late" ones were cast cranks.