Preheat the oven to 350°F. Grease a 2 to 3-quart baking dish or spray with nonstick cooking spray; set aside. Heat a large skillet or Dutch oven over medium-high heat. Add the beef, onion, and bell pepper; cook until the meat is no longer pink, about 5 to 7 minutes. Drain off the excess grease.
Stir in the pork and beans, ketchup, brown sugar, mustard, Worcestershire sauce, vinegar, chili powder, salt, and pepper. Simmer the mixture for about 5 minutes, stirring occasionally.
Transfer the beef and beans to the prepared baking dish. Sprinkle the bacon on top.
Cover with foil and bake for 40 minutes. Remove the cover; continue baking for 10 more minutes. The total cooking time may vary. For really soft, broken-down beans or a thicker sauce, you might like to leave the dish in the oven a little bit longer. The beans and sauce will continue to thicken as they cool, so don’t worry if it looks a little bit soupy when it first comes out of the oven.
Let the dish rest for 10 minutes, then serve. Garnish with chopped fresh parsley or sliced green onions if desired.