They made forge welds then that I believe would be regarded as not possible today.
Gun lovely as-is, most any restoration will reduce its value.
If you do have a passion to remove some of the red rust, I suggest gently scrubbing with honest-to-gosh REAL bronze wool, or a piece of copper, with your favorite penetrating oil. My favorite iron cleaning oil is Automatic Transmission Fluid, but I can be had for Kroil. Even Johnson's Paste Wax or Crisco, if you like. Forget anything with silicone in it.
Do not ever use steel wool, even 0000, or any emery/sand paper on it.