Am not particularly good with a shotgun, Bob, and much prefer big game hunting with a double rifle.  Do like to bird hunt and own a number of shotguns.  All my shotguns are double triggers, only one o/u double, and set up for right handers, but generally have little or no cast to the butt.  Exception is a Darne 10 ga. I had restocked and gave it a very slight left-handed cast.
Also have a number of double rifles (and one bolt action).  The bolt is a left-handed Dakota with no cast to speak of.  The doubles are all right handed, most with a cheekpiece that generally obviates need for right-handed cast, so they are easy to use left-handed.  
Am having Butch Searcy build a sxs in .375 H&H flanged magnum.  That rifle will have the triggers set for left hand, and a lefty cheek piece with, perhaps, a slight left-handed cast.  But, the top lever will be "right handed" because pushing it over with my left thumb just makes better sense and, besides, I don't want any possible confusion with a rifle that might be used against dangerous game!
Regards, Tim