I would seriously not breed him. It is something that will more then likely be passed down the generations. He is a cutie, a great pet but pet. When breeding I think we should all aim to be ethical as possible. t is only fair to the future puppies and future owners.
Also there will be more the likely probelms with arthritus in his back as he ages. Roach back and unlevel tolines are undesirable for a reason, it affects their health.
I would have him fixed and just enjoy your cute little guy.