Here is what I “think” I know. Actually, there were two cranks used in ’59, due to different crankpin bearings & retainers. To be certain of an answer to your question, one would just about have to have the two cranks side by side. The ’57 had longer crankpin rollers than the ’59, but the journal was the same overall width. Because of that difference, the radius at the ends of the crankpin journals differed. Using the wrong crank will cause the rollers to interfere at the radius.
Now the question becomes how about changing the rods and bearings also? It’s starting to get complicated. Might be a difference in wrist pin ends????
I remember going through all this way back in “The Day”, but It’s just been too long ago to remember the details.
.
