Your current hop choice will probably result in a great tasting brew, but if you're going for a Belgian-style farmhouse ale--which it appears you are--I would suggest using Saaz or Hallertau to give it that mildly spicy edge. Willamette is a Fuggles offshoot, so it will probably be a bit more earthy than you would expect for a farmhouse. If that is the character you want, though, looks good to me; I can't see it detracting at all from the recipe.
EDIT: Oh, and a 15 min. addition would probably be very nice. Maybe 0.5 oz of your hop of choice. (As noted above, I'd stick with the nobles.)