IIRC, it was The Remington Autoloading Shotgun first, the 11 moniker was added later.
I can't recall if these had short chambers or not. A smith can give you the answer as well as.....
Deep cleaning the receiver for the first time in a century.
Replacing the fiber buffer in the reciever.
Replacing all the springs and friction pieces.
And showing you how to set up the rings for light or heavy loads.
Once that's done, go shoot it plenty.
Also, in your shoes I'd lean more to conservation than restoration. Those marks add soul. Just clean it, lube it, cherish it.