🚀 go-pugleaf

I think you need to ask around and see if you can locate anyone who
was a phone company employee (or still is) that worked with these
in the past. The phones when installed, were changed internally. 

You do not need an interface, you need the phone jumpers/wires on
correct screws in the phone to make it work correctly on a two wire
set-up. I have seen phone installers work on these, they would change
the set-up inside, depending on whether it was a private or party
line, and whether there were other extensions on the pair.

As it came from Western Electric, who made it, it is designed for
a multitude of types of applications, yours needs to be set up to
the configuration for your two wire application.

If you can locate someone who used to install these, they could tell
you, as they memorized them and could do them blindfolded.