Combine the parsley, breadcrumbs, and orange zest in a small bowl. Set aside.
Add 2 quarts of water, the salt, and linguine to a large saute pan. Cover and bring to a boil over medium-high heat. Reduce the heat to low and cook for 4 minutes or until the pasta is al dente.
Meanwhile, cook the sausage in a 12-inch cast-iron skillet over medium-high heat until brown. Add the green onion and cook until fragrant.
While the pasta and sausage are cooking, whisk together the eggs, cheese, and pepper.
Drain the pasta, reserving 1/4 cup of the starchy water. Add the pasta to the sausage, tossing the pasta to coat in the fat.
Remove from the heat, add the egg mixture, and thin as needed with the reserved pasta water.
Serve immediately with a generous sprinkle of the parsley mixture.