The seasonings for breakfast sausage will work fine. Does your wife use breakfast sausage or some other sage sausage? Give a name brand if you want, that's not a problem.
It's great that you want to start from scratch. It's fun to do. Just remember, the stuffing will probably taste different from what everyone is used to. Not saying it will be bad, just different. For Thanksgiving, people are funny about staying with traditional recipes "like grandma's". Go ahead and do it from scratch but tell folks it may taste different and why so they are not surprised.
"If you want to make an apple pie from scratch, you must first create the universe." -Carl Sagan