Chicken and Rice Casserole

6 pounds cooked chicken
40 ounces converted rice
2 quarts boiling water
2 tablespoons salt
2 tablespoons margarine or vegetable oil
6 ounces margarine, melted
3 ounces onion, chopped
8 ounces celery, chopped
1 pound mushrooms, sliced
8 ounces all-purpose flour
1 1/2 quarts milk
2 quarts chicken stock
1/4 teaspoons white pepper
6 ounces almonds, slivered
3 ounces pimiento, chopped
9 ounces bread crumbs
3 ounces margarine, melted
6 ounces Cheddar cheese, shredded

Dice chicken.

Cook rice according to directions.

Saut