If you want something that can use all the shells you are referring too. I would go with a smooth bore 24" turkey or slug barrell with rifled sights. It will shoot slugs, buckshot, and birdshot decent enough. Cabelas often carries these in their stores as well. You'll just have to search and keep your eyes peeled.
Mossberg 500 Slug Barrel - New! : Barrels at GunBroker.com
Mossberg 500 Slug Barrel - New! : Barrels at GunBroker.com