Preheat oven to 350 degree F. In a large mixing bowl beat butter with an electric mixer on medium to high speed for 30 seconds. Add 2/3 cup of the sugar and salt; beat until combined. Add the 3 eggs and the yolk, one at a time, beating well after each addition. Beat in 1/4 cup of the orange juice until combined. Add the 1-1/2 cups flour; beat until combined. Stir in 1 teaspoon of the orange peel and the 1/2 cup finely chopped pecans. Spread in a greased 15x10x1-inch baking pan. Bake for 15 minutes or until lightly browned (mixture may puff, but will fall when removed from oven).
Meanwhile, in a bowl use a wire whisk to combine the 4 eggs, remaining 1 cup sugar, remaining 2 teaspoons peel, remaining 1/4 cup orange juice, and the 3 tablespoons flour until smooth. Stir in finely chopped chocolate and 1-1/2 cups nuts. Spread over hot crust. Return to oven. Bake for 15 to 17 minutes more or until set. Cool in pan on rack. Drizzle bars with melted chocolate. Cut into diamonds. Makes about 60.