Place the water, salt, and molasses in a 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.
Cover and refrigerate overnight.
The next day, remove the pork from the brine and pat dry. Heat the smoker to 225ºF, add the wood chunks, and place the pork into the smoker. Cook until the pork reaches an internal temperature of 140ºF, 4 to 5 hours.
Once the meat reaches 140ºF, heat the oven to 300ºF. 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 200ºF, is tender, and pulls apart easily, 3 to 5 hours. Remove from the oven and rest, covered, for 30 minutes before serving.