Heat oven to 350°F. In medium saucepan, combine dates and orange juice; bring to a boil. Reduce heat; simmer 15 to 20 minutes or until thickened, stirring occasionally. Remove from heat; cool slightly. In large bowl, combine flour, sugar and salt. Cut in margarine with pastry blender or two knives until mixture is crumbly. Stir in oats, 1 cup coconut and nuts; mix well. Reserve 4 cups oat mixture for topping. Press remaining oat mixture evenly onto bottom of ungreased 13 x 9-inch baking pan. Spread date mixture evenly over crust to within 1/4 inch of edges. Sprinkle with reserved oat mixture. Sprinkle with remaining 1/2 cup coconut, patting gently. Bake 35 to 40 minutes or until light golden brown. Cool completely in pan on wire rack. Cut into bars. Store tightly covered.