That is a really cool story.
My 1950 375 H&H was ordered the same way according to the grandson of the original owner. His grandpa died and they sold his collection. My 375 also has almost the exact same engraving.
I would be very interested what the engravers " mark" was? Whoever engraved mine left his mark on the trigger guard, under the barrel, and wrote in pencil on the inside of the stock in the channel.
Here are some pics of mine:
Here are a couple of the engraver marks:
Under the barrel:
and inside the trigger guard:
I have not tried to figure out who engraved or how to find it.