Huvius

It really depends what you want to spend and if you want the job done absolutely correctly.

To do it right, have the action let down (softened) the tig welding done cleaned up, threads chased, engraved as required and then it blocked up to prevent warping and low pressure gas carburised to the correct case depth. Polished and rust blacked.
Got to be done by the right people. If the gun is worth it you know who to send it to.

Now down and dirty on a NON COLLECTORS PIECE. Many times a copper heat sink is made and clamped in place, or a copper "barrel shank" made and screwed in. An experienced welder with a mig welder can put a cosmetic depth spot of weld in place with great speed and next to no heat spread, certainly no more than was used to spot anneal the places where the mount holes were drilled in the receiver ring in the first place. When cleaned up and rust blacked it will not show.

Holes in the side of the receiver ring ?? What Bubba job required those ?? For that I would only consider option (1)

Regards