In large bowl, cream butter for 1 minute; add sugar and beat for 4 minutes longer or until light and fluffy; beat in eggs.
In separate bowl, whisk together pumpkin, orange zest and juice.
In third bowl, whisk together flour, baking soda, baking powder, salt and spices; stir one-third of the flour mixture into the butter mixture; mix in half the pumpkin mixture; add another one-third flour mixture and remaining pumpkin mixture; sprinkle with remaining flour mixture, raisins and/or nuts; mix.
Spoon batter into greased 8- x 4- inch loaf pan; tap pan lightly on counter to remove air bubbles; bake in 350°F oven for 55 to 60 minutes or until loaf is well risen and golden and tester inserted in center comes out clean; transfer pan to wire rack and let stand for 5 minutes.
TOPPING: Remove loaf from pan, transfer to rack; brush butter over top of cake; combine sugar and cinnamon; sprinkle over cake; let cool completely.