To make the crust: Chill the butter in the freezer for 15 minutes.
Pulse the pecans in a food processor or until finely ground, 6 to 7 pulses. Add the flour and salt, and pulse an additional 4 to 5 times. Add the chilled butter and pulse until the texture looks mealy, 6 to 7 pulses. Remove the lid of the food processor, add the water and bourbon, and pulse until the mixture holds together when squeezed and feels like dough, 5 to 6 more pulses. Transfer the dough to a 1 gallon-sized zip-top bag, squeeze together until it forms a ball, then press into a rounded disk and refrigerate for 30 minutes.
To assemble and bake the pie: Heat oven to 350ºF.
Whisk the eggs, sugar, golden syrup, butter, bourbon, vanilla, and salt together in a medium mixing bowl until combined. Set aside.
Remove the dough from the refrigerator. Cut along two sides of the zip-top bag, open the bag to expose the dough, and sprinkle both sides very lightly with flour. Cover with the bag and roll out with a rolling pin to an 11-inch circle. Open the bag again, and sprinkle the top of the dough with flour. Place the dough into a 9 1/2- to 10-inch tart pan that is 2 inches deep. Gently press the dough into the sides of the pan, crimping and trimming the edges as necessary.
Chop 6 ounces of the spiced pecans and evenly sprinkle in the crust, then pour the filling on top. Bake for 20 minutes. Place the remaining 2 ounces of whole pecans in a border around the edge of the filling. Bake until the center of the pie reaches 200ºF, and a skewer inserted in the center comes out clean, about 10 minutes more. Cool on a wire rack to room temperature before serving, 3 1/2 to 4 hours.