Wash and pat dry the meat. Rub cavity well with lemon juice. Wash rice in cold water, drain, then place rice in a sauce pan. Cover with boiling water; add salt and simmer for 55 to 60 minutes. Add more water when necessary. When rice is tender, drain.
In a skillet over low heat, melt margarine and bacon fat. Saute mushrooms, onions and celery until tender. In a mixing bowl, pour in tomatoes and seasonings. Mix rice and mushroom mixture into this. Stuff bird, then place on a rack in a roasting pan. Pour over 2 cups of water. Cover bird loosely with tin foil and bake at 350 degrees until tender.