Bring a large pot of lightly salted water to a boil. Place macaroni in the pot, cook for 8 to 10 minutes, until al dente, and drain.
Preheat oven to 375 degrees F (190 degrees C).
In a large bowl, mix the cooked macaroni, 1 1/2 cups Cheddar cheese, potato soup, clams with juice, eggs, green onions, onion, Worcestershire sauce, lemon juice, and pepper. Transfer to a large casserole dish, and top with remaining cheese.
Bake 30 minutes in the preheated oven, until cheese is melted and bubbly.