with a"rightie" 870 - I just had a gunsmith install a "leftie" safety in my two 870 Wingmasters, and shoot them off my left shoulder. I never have any trouble with ejected hulls hitting me. The new safety buttons are oversized, so they are easier to find by just feeling for them with your trigger finger.
My Wingmasters (a 12 ga, 2 3/4 inch chamber, and a 20 ga Lightweight Magnum, 3 inch chamber) have such beautiful wood stocks and highly polished blue metal finishes that I could just sit and look at them for hours.
My 870's make me a happy camper!