Hi Dave :-) I know that this is not exactly the recipe that you are trying to replace but this one is very good. It comes from Betty Crocker's Cookbook published in 1971. Serve it in Pepperidge Farms Puff Pastry Shells if you can find them.

Chicken a la King
Makes 6-8 servings as a main course

1 can (6 oz.) sliced mushrooms, drained (reserve
1/4 cup mushroom liquid)
1/2 cup diced green pepper
1/2 cup butter or margarine
1/2 cup all-purpose flour
1 tsp. salt
1/4 tsp. pepper (I usually use ground white pepper)
2 cups light cream
1 3/4 cups chicken broth (You can use canned or 2 chicken bouillion cubes dissolved in the 1 3/4 cups water)
2 cups (or more) cubed, cooked chicken
1 jar (4 oz.) pimiento, chopped (I like to use some or all of the juice in the jar. It adds a nice flavor)
1/2 cup fresh or frozen green peas, cooked (This is optional and not in the original recipe. I think it adds additional color. I actually just throw frozen petite peas into it and they cook quickly as you are heating the chicken.)

In large skillet, cook and stir the mushrooms and green pepper in butter 5 minutes or until tender but not browned. Blend in flour, salt and pepper with a whisk. Cook over low heat stirring until mixture is bubbly, 1 to 2 minutes. (This will cook the raw flour taste out of the sauce.) Remove from heat. Stir in cream, broth and reserved mushroom liquid. Heat to boiling, stirring constantly. Boil and stir 1 minute. Stir in chicken,pimiento and peas (if using them); heat through. Serve hot in Toast Cups, patty shells or Vol-Au-Vents. (My hands down favorite is Pepperidge Farms Patty shells.)

Toast Cups
Heat oven to 375 degrees F. Trim crusts from thinly sliced fresh bread; spread with soft butter or margarine. Press buttered side down into muffin cups. Bake 12 minutes or until lightly toasted.