Place the water, salt and molasses in a large 12-quart container and stir until the salt dissolves. Add the pork butt to the brine and weigh down with a zip top bag filled with 2 cups of the brine to make sure it is completely submerged in the brine.
Cover and refrigerate overnight. Remove the pork from the brine, and pat dry.
Heat the smoker to 225 degrees F. Add the wood chunks, and place the pork into the smoker. Cook until the pork reaches an internal temperature of 150 degrees F, 4 to 5 hours.
Once the meat reaches 140 degrees F, heat the oven to 300 degrees F. Wrap the pork in aluminum foil and transfer to a half sheet pan. Place on the center rack and cook until the pork reaches an internal temperature of at least 200 degrees F and is tender and pulling apart easily, 3 to 5 hours. Remove from the oven and rest, covered for 30 minutes before serving.