Can you help me with substituting some white wheat flour into this recipe?

It's for english muffins. I'd like to use some of my white wheat flour. Also, I don't have bread flour on hand but AP flour. Most of y'all have more experience than I do, so how would you change this recipe to do this?

Recipe:

• 397g lukewarm milk
• 43g softened butter
• 1 1/4 to 1 1/2 teaspoons salt, to taste
• 25g sugar
• 1 large egg, lightly beaten
• 539g Bread flour
  
• 2 teaspoons instant yeast
• semolina or farina, for sprinkling the griddle or pan

1. Note: Thanks to reader feedback, this recipe has been amended as of 1/08/13, as follows: the amount of flour has been increased to improve the dough's consistency; and the cooking time has been increased.
2. Combine all of the ingredients (except the semolina or farina) in a mixing bowl, or the bucket of your bread machine.
3. This is a very soft dough, so you'll need to treat it a bit differently than most yeast doughs. If you have a stand mixer, beat the dough using the flat beater paddle until it starts coming away from the sides of the bowl, and is satin-smooth and shiny; this will take about 5 minutes at medium-high speed. When you lift up the beater, the dough will be very stretchy. If you have a bread machine, simply use the dough cycle.
4. Scrape the dough into a rough ball, and cover the bowl. Let the dough rise until it's nice and puffy; this will take 1 to 2 hours or so.
5. Prepare your griddle(s). Using two griddles allows you to cook all the muffins at once; but since you probably don't have two griddles, you'll need to cook the muffins in shifts. Whatever you use — an electric griddle, stovetop griddle, frying pan, electric frying pan — sprinkle it heavily with semolina or farina. If you're using a griddle or frying pan that's not well-seasoned (or non-stick), spray it with non-stick vegetable oil spray first, before adding the semolina or farina.
6. Gently deflate the dough, and divide it into 16 pieces. Shape each piece into a smooth ball, then flatten the balls until they're about 3" to 3 1/2" in diameter.
7. The easiest way to handle and cook these muffins is to lay them right onto the cold surface you'll be frying them on. That way, you don't have to move them once they're risen; and they won't mind cooking very slowly as you fire the griddle up to its desired heat. If you don't have enough griddle space to do this, sprinkle a baking sheet heavily with semolina or farina, and place the muffins on the sheet; they can be fairly close together. Either way, sprinkle the tops of the muffins with additional semolina or farina.
8. Cover the muffins (a piece of parchment works well), and let them rest for 20 minutes. They won't rise like crazy, but will puff a bit.
9. Cook the muffins over low heat for 7 to 15 minutes per side, until their crust is golden brown, and their interior is cooked through. When done, the center of a muffin should register about 200°F on an instant-read thermometer. If you find the muffins have browned before they're cooked all the way through, no worries; simply pop them into a preheated 350°F oven for about 10 minutes or so, or until they're thoroughly cooked.
10. Remove the muffins from the griddle (or oven), and let them cool thoroughly before enjoying. Remember: use a fork to split, not a knife to cut. Fork-split muffins will have wonderful nooks and crannies; knife-cut ones won't.
11. Yield: 16 large (3" to 3 1/2") English muffins.