[Dr G]

The fourth one from the left? The third one from the right? Correct?
From the pictures, I can see a "C" or a "G" engraved on the back. If there is a letter there and there is no script on the table, then it is a soloist style from the 70s. Also the Selmer script is a much different font.
Maybe it's my eyes or the picture - could you post a closer picture?

Your math is good, but the clue in post #1 says "alto".

Look closer... and slightly to the right. :bluewink: