[tenderfoot]

It is not too late to make the changes. You seem to be clear that you have responsibility in this relationship and how he has turned out, so now you simply need to turn it around.
Finding a great trainer can make things a lot easier. Someone who focus' on your leadership role and not gimmicks. This is about changing your relationship so that he looks to you for the answers and stops thinking the world is his to run. We have worked with plenty of northern breeds and though they can be more aloof and independent, they understand each other just fine so there is no reason they can't understand you.
It sounds like you have loved him well all these years but now its time for trust and respect. You are going to have to earn that. It can happen very quickly if you can make changes quickly. He might also challenge you for a short while because in his mind you have not been a confident leader for the last 6 years and he will be hard pressed to believe you can handle the job. However if you are clear and consistent with the new rules then he will stop challenging and start behaving.
If we worked him we would have an easier time of it because we don't have a history with him. We would be clear about who we are and he would understand and respect that. Unfortunately you have 6 years of old relationship to over come and old habits for you to break. I am not trying to be discouraging but realistic. You can do this and so can he. You are just going to need to understand dogs better and be ready to communicate with him in more of a parental role instead of a roommate.