I am confused???? Do you want to add the Swiss rail like this?
My understanding is that this simple bolts onto the top. Shouldnt need a gunsmith. I think the only mod is cutting the rear stud down, which can be done easly. Or are you looking to have a rail welded on top? Welded will require a different rail, to the best of my knowledge, aluminum cannot be welded to steel. This is the problem I ran into when my rail studs broke off and SIG said get lost. Mine is at a gunsmith now and I will post pics when it gets back. It is suppose to come back with a SAN rear diopter and welded optic rail.