Preheat the oven to 350°. Lightly butter a 5-by-8-inch loaf pan. In a medium bowl, sift together the all-purpose and self-rising flours. In a large bowl, combine the eggs, sugar and orange zest. Add the butter and stir until combined. Add the orange juice. Stir in the dry ingredients and spoon into the prepared pan.
Bake the citrus bread for about 1 1/4 hours, or until the top is golden and cracked and a few crumbs cling to a skewer inserted in the center; cover the loaf with foil halfway through baking. Let cool in the pan for 10 minutes, then transfer to a rack and let cool completely.
The citrus bread can be wrapped and kept at room temperature for 1 day or frozen for up to 1 month.