Bring a large pot of salted water to a boil over high heat.
In a large skillet, cook the bacon over medium heat, turning as needed, until the fat has rendered and the bacon is golden and crispy, 8 to 10 minutes. (You may need to cook the bacon in 2 batches, draining the rendered fat from the skillet between batches.) Let the bacon cool to room temperature, then crumble up into bite-sized pieces.
Cook the pasta 1 minute longer than package directions. Drain, rinse with cold water, and let cool.
Meanwhile, in a large bowl, combine the mayonnaise, sour cream, buttermilk, parsley, dill, lemon juice, garlic, salt, and pepper. Add the pasta, tomatoes, cheese, peas, pimentos, olives, green onion, and half of the bacon, tossing until well combined. Add salt and pepper, to taste. Top the salad with the remaining bacon and more dill, and serve.
