Casting date on a 340

There are a lot of cases like yours, most were cast and built close but there are a fair amount like yours. My 71 demon 340 engine was cast 7/01/70 was assembled 11/16/70,
And then was installed in my demon 4/02/71, not normal but it did happen from time to time. Problem is nobody really knows why unless we find the guy who was around back then.. That was in charge of the engine plant.