Any advice?

So I am really trying to get the Glenfield Model 75 C Marlin 60 off of my bench. This is my rifle, given to me for the work I did on the other 60. My problem is this. The magazine tube ring that attaches the tube to the rifle was loose. I attributed that to the fact that the dovetail looked pretty beat up. I bought a new one and it arrived today. 

New one on the left, old one on the right. That ring is supposed to go here:

So I have heard several methods to fix this. The rifle is a beater cosmetically, but I would like to keep it around. The options I have been told about are:

Use a punch to rough up the surface of the magazine ring on the bottom where it meets the barrel.

Use a punch to beat the dovetail ON the barrel to hold the ring in place after it is installed.

Use epoxy on the barrel to raise the base of the dovetail.

Use a brass shim to go the same as the epoxy.

Any help out there? I don't know how to proceed. I think any of the above would work.