Rolland, the Rusan brand is made in Croatia I believe.

I would be using original factory type Steyr mounts such as those made after the war, they suit the split bridge really well. Those are shown in the link above by Rothhammer. The only thing you will have to work around is that the rear mount on the factory base is designed to mount on a flat surface like on the MS whereas your rear bridge is convex on the outside.

You can also use a combination of a Recknagel pivot mount on the front and a genuine style base and ring at the rear.

Matt.