It makes no sense to put a vin on an engine ever, its not a vehicle.
There were and are many other uses for automotive type engines other than vehicle usage. Such as marine, pumps, equipment, welders etc. It makes more sense to serialize them in production and add things like date point of origin etc. But then lots of that sort of info is usually included with the casting numbers.
In those days especially you just wouldn't want to stamp the same number the body was supposed to have, why??? Huge nightmare making sure that same engine was going into the proper numbered car or truck. I'm not sure about what your saying about 61 plus cars, unless an owner decided to do that at rebuild time.?? I don't know.
