You'd lap in the front pivot to reduce stress on the scope during mounting/dismounting.

The barrel band on front ring would have to be bored to suit barrel diameter.

Your ring centre heights would have to be correct (to reduce bending stresses on scope). Boring them while both held in a jig (or on an action) would achieve this.

As long as your rings were split you could position them to suit bases/scope.

After that there's a windage screw/screws in the rear ring that goes into the rear base.

I think they're the best of the Mannlicher mounts that I've seen. Some of the rest look like crude scaffolding done as an after thought.

Rings to suit existing bases would also have to be an attractive offering. Though you'd need the rifle to fit them.

Trouble is, if I could build these mounts, then I'd "have to" have a Mannlicher.