Tom,
First of all, I think you should move that scope forward till you get the top turret between the rings. In my humble opinion, your scope is set way too far to the rear. Depending on the caliber of your gun, you might get a real whack from the scope if left that way, especially if you are shooting over a bench sitting down. I try to keep the rear end of my mounted scope even with the rear of the top lever or there about.

Since you have inlet the dovetail parts into your rib, you can't put in a rear sight for the front ring to snug up against for a recoil lug. You could put in a short threaded piece of steel rod for it to sit against but that seems a little sloppy to me. What I would suggest to you is that you make another longer, front mounting piece and leave a short piece of metal rail sticking up a bit all the way across for a recoil lug, That way you can still use you same mounting holes for the screws.

You will not be able to harden the rings enough to do what you want without the use of a recoil lug. Ask me how I know this! I have had a scope fly clear off one of my guns trying to do the same thing! You must have a recoil lug to stop the scope from moving forward but one in the rear is not needed.

I use Talley lever set rings and cut my dovetails right into the sides of my quarter rib. If you start with a 1/2 inch wide rib and dovetail it, You can then slide the scope onto it from the rear with the gun opened up. If it has a Greener extension on it, or something else that keeps you from sliding it on from the rear, then you will need to machine in slots from the top in order to drop the rings in and slide everything forward.

If you do this, Talley rings can be file fitted somewhat in order to come up with two rings that just fit when tightened. By turning the levers a half turn to the rear, they will release and slide off the rib. If they get a bit loose, you can tighten them up by moving the tightening screws in the levers by one flat on the screw shoulder, and if really bad, you can take the mounting section off and file just a little bit off the main part to get them to close tighter.

The reason for using the Talley rings is because they don't have the cross screws hanging down below the dovetailed areas. Other rings sometimes use those as recoil lugs, but I never thought that was strong enough anyway.