To answer some of your questions-- I have not seen any embossing on the frame. If the frame dropouts had a name, it was long gone. The fork clearly has "basso" on the dropouts.
The down tube is definitely ovalized at the bottom.
Upon further review, there is a serial number on the bottom of the BB shell, but I can only read a "5". The rest is covered with gobs of paint. If it matters, the serial number is on the non-drive side, and appears to extend circumferentially around the shell, with the top of the numbers near the non-drive side crank.
I don't know the threading. I haven't tried to take off the cranks yet. And the battery is dead on my micrometer.
Jared
PS: I now have three frames that need paint removal. Sounds like a good reason to buy a harbor freight sandblaster.