1. With a fork, prick bottom and sides of unbaked pastry in pan at about 1-inch intervals. Bake in a 375° regular or convection oven until golden, 15 to 20 minutes; let cool on a rack.
2. Meanwhile, in a bowl, mix cream cheese and 1/2 cup sugar until smooth. Spread evenly over bottom of cool pastry.
3. In a blender or food processor, whirl 1 cup sliced peaches, remaining 3/4 cup sugar, orange juice, and cornstarch until smooth. Pour into a 3- to 4-quart pan; stir over medium-high heat until mixture boils and thickens, about 4 minutes. Remove from heat and stir in lemon juice.
4. Add remaining 5 1/2 cups peaches to hot peach glaze and mix to coat slices. Let cool until tepid, about 25 minutes, then scrape onto cream cheese mixture in crust.
5. Chill, uncovered, until firm enough to cut, at least 3 hours. Cut into wedges and serve, or invert a large bowl over pie (it shouldn't touch fruit) and chill up to 1 day.