The engine block was replaced. The trans is Jan 1968. This was in an Imperial due the dual oil pressure senders and that vacuum tank on the back of the intake. Those spark plug heat shields were on every BB made and are common. The AC line brackets are 1965-1968. The trans linkage to the carb is good setup.
The block VIN number would be on the pass side front where your tire is, and its bare there.
mice made nests in the cylinders which is very bad. Pee and water so the pistons get stuck to the cylinders. Heads need to come off and see what’s in the cylinders, clan it up, soak with ATF and acetone if not too bad. But the whole thing needs taken apart and cleaned up. Crank is probably good. Don’t burn the crud in the cylinders, no benefit, more cleanup later. Valve springs are not good from the rust.
So the car had 27K on the odometer. And block is January 1972. So is that 172K miles on the car and it needed a worn out engine replaced?