Is One Of These An Appropriate Substitute For A Stewing Hen For Making Chicken Stock?
From Poultry Meat Processing by Casey M. Owens and Christine Alvarado:


A stewing hen is the 52 week old breeder bird.

I can only guess to Roux and Peterson's suggestion, but it is probably based on size, and/or maybe that the maturity brings flavors to the stock that a young hen does not.

I would avoid the Cornish hen. They are very young and small.

Out of the options you list, you'll be OK with a large Baking hen.

Suggestion, if you have any Asian supermarkets nearby: 


check out their poultry, sometimes they have better than the factory fed chain stores
pick up some chicken feet and add them to your stock, they add a great color and flavor