Need help with this 340 block id.

As those stampings under the head both look factory to me, could this be a engine that failed a test before it was designated a vehicle and then some how founds it's way back into the production line months later? Seeing only one Vin stamp, just speculating. Don't see any of the skull and cross bone markings :). But if it was mine, i think i'd do some measurement checking on teardown for some odd bearing or lifter numbers. I'm just saying this out of curiosity. What do you guys think?