Fry the bacon in a skillet over medium heat until slightly crisp, 12 to 15 minutes. Drain on paper towels; set aside to cool.
Combine the mayonnaise, buttermilk, sour cream and garlic in a large bowl. Add the vinegar, Worcestershire sauce, 1/4 teaspoon salt, 1/2 teaspoon pepper and the cayenne and whisk until the mixture is smooth.
Chop the bacon into pieces. Cut the iceberg head in half, then cut each half into 2 wedges. Spoon dressing over each wedge so it drips down the sides, then sprinkle with the cheese and bacon.