Hi,
I don't think it's too late. Your dog might be a bit old to become a field champion, but that doesn't mean it can't provide many years of enjoyment afield for the both of you.
Look at it this way, your dog already hunts. What we do when we train our dogs to "hunt" is nothing more than obedience - When, where, and how we want it done. So do you think you can teach your dog some simple obedience work?
One last thing, unless you are interested in playing doggie games, i.e. trials and such, don't get so hung up on how some book or anyone else thinks your dog should hunt. Your dog should please you in what it does and how it hunts. And remember, it's a partnership between you two. There needs to be give and take in the relationship.
Good Luck!
dalee