Pressure cooking is always an option! It will soften any old rooster. You can pressure cook with a bit of moisture to eat as is... or you can pressure cook in a lot of moisture (2+ quarts?) spices, veggies. Once it is finished cooking remove the carcass, strip the meat, save the meat for enchiladas, stews, etc and then continue to pressure cook the carcass bones, skin, spices and veggies etc to complete a stock. I can usually get all of the meat and about 2 quarts of good stock from one really old rooster. (Old roosters seem to make twice the stock of a more moderately aged bird- and old rooster makes the best stock- just remember to add the feet, wing tips, neck, etc.)