You bring up some good points.
First, I do not think there even was such a thing as an 'outdoor enclosure' in 1959. I believe the NEMA designations came about in the early 70's ... and I do know we were well into the 80's before UL recognized them (UL had their own criteria until then).
Also note the mild corrosion. Panels of that time were often just painted; only recently have they been required to be galvanized as well as painted.
The 1/2" EMT to the right posed another problem: swollen insulation. That is, the cloth/rubber wire insulation had swollen with time, and it wasn't about to come out of that pipe. So, I simply made it fit the panel as best I could; that's why it's a bit off-plumb.
As for the siding, the property owner (and HVAC contractor) claimed he would patch / seal the old meter opening. As there was a siding crew working (literally) next door at the time, I would not be surprised if he conned them out of a scrap piece or two.
This job, like most, had plenty of other little 'quirks.' It was particularly of concern to me because it was my first service change, first permit pulled, since I "went solo." I had done work for the customer before, but never on my own, and he was a bit nervous. Meanwhile, the city has laid off its' entire building department, and the inspections were carried out by parks department employees (oh joy!). The PoCo, having just undergone a re-orginization, had also made some major changes in how these service changes were to be done.
