Not sure if you guys have seen the windage adjustable rear scope rings made by Leupold, redfield, and a number of other manufacturers, but the bottom of the screw head is radiused and undercut to grip the edge of the scope base to hold the ring in place. This means the screw center is above the base, threaded into the ring side, so the center of this base cut radius would actually be above the top of the base. You would need a cupped end mill cut from the side of the base in the proper radius, which you would probably need one of these scope ring attachment screws to measure- or try to extrapolate from the existing base.
An easier method would be to buy Leupold's gunsmith bases, which are plain blocks with the machining already done except for mounting screws and radius to match the barrel or action. I've used them on a couple rifles and they are really handy. The one you would need for the windage adjustable sight would be a Leupold #50033. I believe the dovetail cut on the sides of this base is for the old Unertl style rings with the clamp bases and the cut shown is to adapt to the Leupold style windage adjustable style rings- but I could be mistaken- it has happened before, just ask my wife.
Bob