I just had an idea. Most here seem to advocate a natural POA and leveling the scope to gravity with NPOA on the rifle. But this is hard because you have to be holding the rifle while you are doing it.
How about a system that will clamp to the gun level and true to the rifle, but shows the exact degree of offset in the NPOA.
Then you put the scope and rings in one of the leveling devices above and look at a plumb bob with a graduated circle imposed on it. You then cant the reticle in the rings to the exact NPOA offset.