I do plan on restocking in a pistol grip. I like straight stocks for my shotguns, but for this rifle, i think a pistol grip is best.

I sure hope the regulation has not changed after installing the ribs. The regulation is set by the two spacer blocks inbetween the barrel tubes. In in the middle and one at the muzzle. And all my regulation was done off a lead sled so it is independant from human error pretty much. So the optics or mounting have nothing to do with it regulation is separate from sighting in.
Obviously i will shoot again to double check after installing the top rib.