Bill;
After I made the above post, I looked at the photos you posted again as well as the photos of the other firearm you posted. The width of the rib on your M&G may be wide enough to dove tail that rib to use the Talley quick detachable scope rings and removing the original base. I have dovetailed double rifle ribs for the use of Talley rings and the dove tails can hardly be seen. If your rib is wide enough 12 mm or so, the current scope base could be removed and when the scope is mounted no little evidence of the original screw holes will be seen. If your rib is not wide enough or if you want to retain the original mount, that mount could be machined to fit the Talley rings base as well as dovetailing the area machined to fit the Talley ring base. Talley also makes dovetail base scope rings that are not quick detachable that you could use.
https://www.talleymanufacturing.com/product/1-screw-quick-detachable-ring-w-lever/There are several considerations to be made in the work I mention above and that is to have the scope that you are going to use at hand, so that the gunsmith can place the scope rings dovetail exactly where the need to be in order not to interfere with the scope adjustment block; and the length that the scope rings need to be "apart" in order for the scope adjustment block to fit into the mounting as well as eye relief for you. And finally the scope needs to be high enough where you can easily use the top lever to open the barrels.
Regards;
Stephen Howell
