In a large bowl, combine ground lamb with the bread, allspice, coriander, garlic, onion, savory, and salt and pepper, and knead well. The mixture should hold its shape. Break into 5 sections, each about the size of an orange, then divide each section into 6 balls. Knead and flatten each to a thickness of about 3/4 inch. Cut the bacon slices into squares and thread them on 6 wooden skewers alternately with the meatballs. Smooth the edges with your hand so they will cook evenly. Cover and refrigerate overnight. When ready to cook, broil or grill with moderate heat, turning every 5 minutes. The surface will be crusty and the inside cooked through within 25 minutes. To serve, heat and split the pitas and serve the gyros with the bread, tomatoes seasoned with the vinegar and oil, parsley and yogurt in separate dishes.