I think that in this same forum I read somewhere that those buttons with "extra quality" words on them were the saws that sawmakers made on a regular basis to be sold to ironmongers that sold them as if they were specially made for them; something similar to what nowadays is called "white brand" I guess.
However the way the front end is cut with that little thingy on it makes this it is a Disston saw, but I'm no expert at all, so I won't put my hand on the fire for it.
If you do not want to use elbow grease, citric acid will remove the rust with no effort at all.
Look forward to see it restored Rob!