A lot of it will depend on the skill/comfort level of the shop tech. For this particular issue I would take it to the most reputable and respected shop in your area.
Sometimes, you'll be fine even at only +/-1cm. So, 3cm should be a healthy and safe distance. A lot of this depends on how ugly your pullout (i.e. the removal of the screws & binding pieces) ends up being. It will also depend on the construction of the ski itself: what kind of core is it, is there metal, was there a tearout prior to remount, ...
My guess is you're completely fine, people have certainly remounted MUCH closer.