Short answer: Yes.

Long answer: Depends on what your going to try and train him for... Retrieves, tracking, trailing, pointing, walking upright, etc.

If your going to have a retriever, I would recommend SmartFetch by Evan Graham or Total retriever by Mike Lardy, (who we all know handled Lean Mac for a couple years).

The most challenging part of an old dog is the habits. You have to "Force Break" almost all of their old "bad" habits, simply because they dont know any different. Thats very slow, very repetitive process, it could easily be a year before you have the dog where you want them. If the dog already has solid OB, it should help give you a platform to work from.

You may figure out that the dog is going to do what you want with very minimal training.. Or that you may never get what you want from the dog, in that case, just enjoy the good times you have with your "pet" and get yourself a puppy or a started dog for your Hunting.