Combine lemon juice and orange juice, sprinkle gelatin over juice, and let stand 5 minutes.
Combine 1 cup sugar and flour in a saucepan; stir in milk.
Bring mixture to a boil over medium-high heat, reduce heat, and cook until thickened, stirring constantly.
Beat egg yolks until thick and lemon colored.
Gradually stir about one-fourth of hot mixture into yolks, add to remaining hot mixture, stirring constantly.
Cook over medium-low heat, stirring constantly, for 2 minutes.
Remove from heat, add gelatin mixture, stirring until gelatin dissolves.
Stir in peaches and lemon rind; let cool.
Chill peach mixture until thickened.
Beat egg whites (at room temperature) until foamy, add 3 tablespoons sugar, one tablespoon at a time, beating until soft peaks form.
Fold egg whites into peach mixture; set aside.
Line bottom and sides of a 13- x 9- x 2-inch dish with ladyfingers, placing rounded sides of ladyfingers toward outside of dish.
Spoon peach mixture into dish; cover and chill 8 hours.
Spread whipped cream over top before serving.