wise choice adding noodles, but not so sure about the sour cream/egg topping, it seems that the topping will be fluffy and I don't see that going well with your more dense filling, perhaps a more crunchy topping would accompany the savory filling. such as:
typical french fried onions
one cup bread crumbs tossed with 1/4 cup of butter (before baking)
crisp bacon, mixed with any of the first 2 toppings
1/2 stack or ritz or ritz-like crackers finely crumbled with 1 tbsp of butter melted
but it does seem as if your casserole creation already exists:
Green Noodle Chicken Casserole
2 cups chopped cooked chicken or 1 chicken,
cooked with celery, onion, salt and pepper
2 1/2 pounds collard greens
1 cup chopped celery
1 cup chopped onions
1/2 cup (1 stick) butter
1 jalapeno chopped finely
1 (6 ounce) jar pimento or 1 (6 ounce) jar Spanish olives
12 ounces green noodles
2 cups stock (or 1 cup stock plus two cans celery soup)
1 green bell pepper, chopped
2 cans cream of mushroom soup
1/2 pound Velveeta cheese
If using whole chicken, boil to cook, then remove chicken from pan and save stock. Cool chicken, remove skin, de-bone and cut into bite-size pieces.
Cook collard greens in boiling water about 15-20 minutes. strain.
Sauté in butter the celery, onion and bell pepper. Add mushroom soup, pimentos, jalapeno, cheese and 2 cups stock.
Cook green noodles in reserved stock until tender. In greased casserole, place layers of noodles, then chicken and greens, then sauce, alternately until all are used. Cook covered in 350 degree F oven until heated through and bubbly. Cook covered until just before removing from oven.
Serves 16.