@Fretting out ya done good, buddy! That is a looker, and if it plays and sounds half as good as it looks...
I love a good guitar mystery, and I've enjoyed reading this thread. I know the Harmony brand best. My Dad had 3 Harmony made guitars throughout the '60s into the early '70s. I associate those segmented/stencil-style
f-holes with the '30s and '40s, but again that's more with Harmony brand.
I don't personally know the history of the Metro brand or the Concerto model, but I think I see in the third pic you posted something might yield another clue. Looking through the
f-hole on the left/bass side, I see what appears to be stamped information on the inside of the back of the guitar.
Harmony did this with their guitars, the model and serial numbers on the bass side, and a date stamp on the right side. For example, in my Harmony Broadway, looking through that
f-hole on the left/bass side, you see "1286 H954." H954 was the catalog model number of the Broadway. The four digits prior to the model # has been called a "batch number" with unknown significance. It seems logical to me to take this number to mean the 1,286th unit produced to that point in the production year. It has been said that in the last three decades of the Harmony brand (1945-1975), they produced 10 million guitars. If so, it's believable to me that they could have produced several thousand Broadway models in 1953.
And looking through the
f-hole on the right/treble side, by the pickguard, is stamped "F-53." The date stamps always began with either an "F" or an "S". Different theories have been advanced as to the significance of the letters. One was that "F" stood for Fall and "S" stood for Spring. However, one Chicago factory worker interviewed stated that the production year was divided in two, and that "F" stood for the First half of the production year, with "S" standing for the Second half.
For a long time I believed the first theory, until I read the theory based on a factory worker's testimony. That sounds more plausible to me. Either way, the "53" is the year my Broadway was made, and I have the same born on date, so it's my birthyear guitar.
I bring all this up not to highjack the thread to discuss a different brand, but because I think it applies in your case. I saw in that aforementioned third pic what looked like stamped information. I copied your pic, enlarged and rotated it, and it looks like this...
View attachment 867526 Of course, you could see this more clearly. I was just bringing up the point because whoever made your guitar, it seems they followed a similar practice of stamping information inside their guitars. It might help you determine a model # or batch # or date stamp.