As I was growing up in New England in a family with six kids, we would have these every Saturday night. My mother made them without the maple syrup and my father would use maple syrup. I use both.
Soak beans overnight. Bring to a boil in same water and simmer until tender, about ½ hour or more (put a couple of beans on a spoon and blow on them, if skin peels back they are ready for cooking). Drain, reserving bean water. Preheat oven to 250 degrees. Place beans and salt pork in casserole or bean pot. (If you scour the salt pork put beans in pot first and lay the salt pork on top with rine down). Combine i¿½ cup bean water, brown sugar, mustard, onion, molasses, ketchup, garlic, and maple syrup. Pour over beans, cover, and bake 6-9 hours or until beans are tender. If beans become dry add some of the reserved bean water. Uncover the last hour of cooking. A stone bean pot works best but any Dutch oven kettle will work.