I also have seen this sign in person but have a different interpretation on it. You did not include a picture of the back of the sign, and it is clear that it is very old (see picture). From the flaking around the mounting holes it is obvious the paint is old as well. Granted, this is a hand painted sign and was not mass produced, which would explain why nobody has ever seen it and why the logo doesn't match exactly. The gentleman that owns it says it was hand painted for one of the stations it hung on and was taken down years later by the owner. . I believe the sign to be an original one of a kind sign, that is very interesting for sure. Just my opinion.