Preheat oven to 350 degrees . Place the blueberries in the pastry shell and set aside.Combine 1 cup sugar, 1/3 cup flour, and salt in a medium bowl. Add eggs and sour cream, whisk until well blended. Pour the sour cream custard over the blueberries.In another bowl, combine both white and brown sugars and 1/2 cup flour. Cut in the butter with a pastry blender until the mixture resembles coarse crumbs. Sprinkle the topping over the sour cream mixture and berries in the pie shell.Bake in the preheated 350 degree oven for 50 to 55 minutes, or until lightly browned. Cool on wire rack.  Refrigerate after it cools.  Note...If the crust starts to brown more than you'd like, place foil over the crust and continue baking.