Combine 1 1/4 cups sugar, cornstarch, butter, lemon rind, salt, and egg yolks in a heavy saucepan; stir well. Pour boiling water over sugar mixture, stirring well. Cook over medium heat 5 minutes or until thickened and bubbly, stirring constantly. Remove from heat. Stir in pineapple and lemon juice. Pour filling into pastry shell.
Beat egg whites (at room temperature) and cream of tartar until foamy. Gradually add 1/4 cup sugar, 1 tablespoon at a time, beating until stiff peaks form. Spread meringue over warm filling, sealing to edge of pastry. Bake at 350° for 10 to 12 minutes or until golden brown. Cool to room temperature.