I'm confused, why does a left hand ejecting shotgun have to have special left hand barrels? Mind you I don't own an 870 so have no experience with the things.
That's the beauty of an Ithaca Model 37. Bottom ejection, no problems
Also don't forget about the Browning BPS. Bottom ejection like the model 37 and with a top tang sliding safety. This is a true ambidextrous shotgun and if you ask me it's a really a fine pump shotgun.