If the dihedral does not even out when the wing is bolted on, then it would take very little shimming on one side or the other to bring them within 1/4" of each other, which would be more than enough precision. You'd want to do this with the vertical fin straight upright, of course. Even if you did nothing, it would be beyond most any flier to notice anything wrong in flight behavior. It's good to aim for precision to the best of your ability, but models can be noticeably out of alignment and still fly well enough.