Combine 1/2 cup sugar, cornstarch, and salt in a heavy saucepan. Gradually stir in the reserved liquid. Cook over medium heat 10 minutes or until thickened and bubbly, stirring constantly. Remove from heat. Add butter; stir until butter melts. Stir in cherries, lemon juice, and walnuts. Pour filling into pastry shell.
Beat egg whites (at room temperature) until foamy. Gradually add 1/4 cup plus 2 tablespoons sugar, 1 tablespoon at a time, beating until stiff peaks form. Beat in almond extract. Spread meringue over filling, sealing to edge of pastry. Bake at 350° for 10 minutes or until meringue is lightly browned. Cool to room temperature. Chill.