Used my new pumpkin pie tin today for the first time, and no surplus mixture! ;D
Using a typical traditional pumpkin pie recipe (2 cups cooked pumpkin, 1 can evaporated milk, 3 eggs, 100 grams of sugar, 3 tsp of mixed spice), makes up to a volume of just over 1 litre. You have to add a volume for the pastry, some 350 ml. Therefore, you should aim for a total volume of your pie tin of some 1.5 litres, which you can check by first filling the pie tin with water and then pour the water into a measuring jug.