Is possible, but usually salavge numbers are numbers and letters in a code sequence identifying date of aquisition and partial vin of vehicle removed from.
it could be anything really, could even be there from assembly when new.
I'd be inclined to say no, just cuz the upper hose still has the OEM clamps still in place, most folks loose those cuz they can be a PITA at times, not have enough spring tension to reseal after opened a few times.
I'd say take a closer look at those hose clamps, the one at the rad. looks "clean" and the one at the eng. looks rusty(sitting out in the open at the yard?)
If it was an engine swap, isn't there a VIN on the engine you could compare to other VINS on the vehicle? I don't know all the places VINS are located but I'm pretty sure most cars have them on the engine, frame, dash, and tranny.