Sift flour, sugar, Clabber Girl Baking Powder and salt together in a mixing bowl. Cut in butter or margarine and shortening until mixture is texture of coarse crumbs. Add milk and eggs; blend just until ingredients are moistened and dough forms. Cover dough and chill at least 1 hour.
Cream brown sugar, butter or margarine and cinnamon until smooth. Set aside. Roll out dough on lightly floured surface, into 1/4' thick rectangle. Spread filling evenly on dough. Sprinkle 1/2 cup chopped pecans. Roll up dough, start with long side, jelly-roll style. Cut into generous 1" thick slices.
Combine brown sugar, corn syrup and butter or margarine in saucepan. Bring to a boil, reduce heat to simmer. Cook 2 minutes, stirring until sugar is dissolved. Pour evenly into the bottom of a 9" x 13" pan. Sprinkle with 1/2 cup pecans. Arrange rolls, cut-side down, in pan.
Bake in preheated 375 degree F. oven for 25 to 30 minutes, until golden brown. With cookie sheet or platter against baking pan, turn upside down. Cool until slightly warm and serve.