Combine 3/4 cup sugar, flour, and 1/2 teaspoon salt in top of a double boiler. Gradually add 1 1/2 cups water, stirring well. Place over boiling water, and cook, stirring constantly, until mixture thickens.
Beat egg yolks until thick and lemon colored. Gradually stir one-fourth of hot mixture into yolks; add to remaining hot mixture, stirring constantly. Cook over boiling water, stirring constantly, 5 minutes or until smooth and thickened.
Remove from heat. Stir in orange rind, orange juice, and lemon juice, mixing well. Spoon filling into pastry shell.
Combine egg whites, 1/2 cup sugar, dash of salt, and 2 tablespoons water in top of a double boiler; beat well. Place over boiling water. Beat at high speed of an electric mixer for 1 minute. Remove from heat; beat 1 minute or until soft peaks form. Spread meringue over filling, sealing to edge of pastry. Arrange orange sections over meringue; sprinkle with coconut. Chill.