Identification numbers on front of 273 block

As old as these girls are it is almost impossible to second guess their history, unless maybe you buy a car from a family who KNOWS the cars history from new, etc.

Keep in mind that all my life, there has existed overhauled exchange engines, "long" and "short" blocks. People thought nothing of buying an exchange engine and tossing it in the vehicle. Same goes for transmissions. I once had a 60 Falcon for a short time before I joined the Navy in 68. I had tore up the tiny 3 speed gearbox, and bought an exchange from the local junkyard. They said they "went through them." Nothing to it. Threw it in and go.