Preheat oven to 375 degrees. In a large bowl, stir together flour, sugar, baking powder, baking soda, salt and allspice. Using a pastry blender, cut in butter until the mixture resembles coarse crumbs. Make a well in the center; set aside. In a small bowl, beat eggs slightly; stir in buttermilk. Add all at once to the flour mixture. Using a fork, stir just until moistened. Fold in chopped pears. Turn dough out onto a floured surface. Quickly knead dough by gently folding and pressing for 10 to 12 strokes, or until nearly smooth. Pat or roll lightly to a 1/2-inch thickness. Cut dough into shapes with a 2 1/2-inch biscuit cutter, dipping cutter into flour between cuts. Place dough rounds one inch apart on an ungreased baking sheet. Bake for 10 to 12 minutes, or until golden. Cool on the baking sheet for 5 minutes, then transfer to a wire rack. Sift powdered sugar over the tops.