Honestly I havent checked to see what it would do, but there shouldnt be any change at all. You should be able to take off the sight, mount your scope, realize just how weird a scope feels on a lever gun, then put your Skinner "Express" sight right back on !!!
(I hope the humor isnt lost here... A couple of my Marlins wear scopes and although its not my first choice, it serves a purpose on those rifles..
In a nutshell... I'd say no worries, take it off, put it back on, shouldnt be any change of Zero. That is one of the beautiful things about the Express compared to our standard 336/1895 sight which has a screw located under the dovetail. Nothing has to be moved for access to the screws.
Hope that helps!