Hello David, I’m surprised that no-one your side of the pond has responded as I can see that quite a few have seen and read your post.
Have you seen this AL thread, it might be of some help as its a similar Victor:
https://www.antique-locks.com/showthread.php/1321-WTB-lock-and-key-for-Victor-safe-small-door-hinge-acorns?highlight=Finials
Your safe is the early pattern before they added the separate handle to throw the boltwork. Most seem to have the gold seal/medal crest on the door commemorating their gold award at the 1904 St Louis Expo.
The thread link above is definitely worth a look, all I have is an old 1950s safe mans guide from the Locksmith Ledger which does cover your early style Victor but unfortunetely doesn’t answer any of your questions!
RE; the Fireproof filling, if the safe has already been filled and patched then wouldn’t worry too much about it, unless you specifically want to analyse exactly what’s there originally and then try to mix up stuff to match there seems little point on something that age which is probably now of questionable fire resistance anyway.
The 14X marked in the filler could be anything, more than likely the manufacturers batch number or stock/spec , but a dealer, safe tech or even a previous owner in the distant past could have done it and no-one would know for sure!
