Heat oven to 400 degrees. On a lightly floured surface, roll out dough to an 1/8-inch thickness. Cut into six 7-inch-diameter circles; place in six 4 1/2-inch pie pans. Crimp edges, and refrigerate until firm, about 30 minutes. Remove from refrigerator, and prick bottoms of shells with a fork.
Line piecrusts with parchment paper, and fill shells with dried beans, rice, or pie weights. Transfer to oven; bake until edges begin to turn brown, about 10 minutes. Remove paper and weights. Continue baking until golden brown, about 7 minutes. Transfer to a wire rack to cool.
Sift together 1 1/4 cups sugar and cornstarch in a medium bowl. Stir in 2 cups water, and mix until smooth; set aside.
In a nonreactive saucepan, combine lemon juice, 5 egg yolks, and pinch of salt. Set over medium heat, and stir in cornstarch mixture; cook, stirring constantly, until mixture comes to a boil, about 14 minutes. Remove from heat; stir in the lemon zest and butter. Pour filling into a bowl, and set aside to cool, stirring occasionally.
Pour lemon filling into the six piecrusts. Cover; refrigerate until firm, about 1 hour.
Heat broiler. Bring a medium saucepan of water to a simmer. Combine 7 egg whites, the remaining 3/4 cup sugar, and 1/4 teaspoon salt in bowl of an electric mixer. Hold bowl over simmering water; whisk until the mixture is warm and the sugar has dissolved, about 3 minutes.
Return bowl to mixer fitted with the whisk attachment, and beat until stiff peaks form. Using an offset spatula, spread each pie with meringue so the filling is covered and the meringue touches the edges of the piecrusts. Transfer pies to broiler, and lightly brown the meringue, watching constantly, 30 to 45 seconds. Remove from broiler, and place on a wire rack to cool to room temperature. Serve.