In a medium saucepan, combine the prunes with enough water to cover them by 1/4-inch. Bring to a boil and reduce the heat. Simmer gently, uncovered, for 20 minutes. Add 1/2 cup of the port and bring back up to the boil. Immediately reduce the heat to low, cover the pan and simmer for 15 minutes. Remove from the heat, drain the prunes, coarsely chop, and set them aside. Reserve the liquid. In a medium skillet, heat the olive oil over medium heat. Saute the pine nuts, stirring frequently for 1 or 2 minutes, until golden. Add the prunes and the remaining 1/4 cup of port to the pan. Continue cooking and stirring until the liquid is reduced to a glaze. Stir in the salt and pepper and cool to room temperature. Cut horizontally into the edges of the pork chops almost to the bones to create a pocket for the stuffing. Stuff the chops loosely (if there is leftover stuffing reserve it for the sauce).
Secure the edges of each chop with 2 toothpicks. Season the chops generously with salt and pepper. Preheat the oven to 350 and place a roasting pan in it to heat it up. Heat a large, heavy and well-seasoned skillet over medium-high heat until very hot. Sear the chops for about 1 1/2 minutes on each side. Transfer the chops to the pan in the oven and finish cooking them for about 20 minutes, until the chops are done through. Meanwhile, add the oil to the skillet which you used to sear the pork. Over medium-low heat, saute the shallots for 6 to 8 minutes, until translucent. Add the port, beef broth, and the reserved prune-cooking liquid to the pan and, if there was any filling leftover after stuffing the chops, add it now. Increase the heat to high and reduce the liquid, uncovered, until it is thickened and saucy, stirring frequently. Stir in the butter and lemon juice until the butter is completely absorbed. Serve the chops immediately, spooning the sauce over the top.