David,
Good formula. I don't know how accurate it is, but the concept is right on. It can take as much as 3 hours per pound but with a bigger piece of meat, it doesn't take as long per pound.
Craig,
If you do a search on chuck roast, you will find a link to a chuck roast cooking method by a member named Stogie. That will get you going. It's a great cook. I love chuck roast.