To soften noodes, place in a large bowl. Cover with very hot water and let stand for 10 to 12 minutes, or until softened but still firm (pinch them to check). Rinse well with cold water and drain.
In a small bowl or measuring cup, combine stock, lime juice, fish sauce, sugar, and chili sauce.
Heat a wok or large skillet over medium-high heat and add 1 Tbsp oil. Add beaten eggs to hot pan and swirl to coat bottom of pan. Cook until starting to set, then stir to break into pieces. Remove from wok and reserve.
Add remaining oil to wok. When hot, add garlic, shrimp, and chicken and stir fry for 2 minutes, or until shrimp and chicken are just cooked. Stir in noodles and reserved sauce mixture and cook for 1-2 minutes, or until noodles are soft but not mushy.
Add 1 cup of bean sprouts and cooked eggs and toss to combine.
Turn noodles onto a serving platter. Sprinkle with remaining bean sprouts, green onions, peanuts, cilantro, and chilies, if using. Garnish with lime wedges.