@CarstairsCowboy
Please see no malice in my previous comments. I only shared references to help you evaluate your blade. As others have already mentioned, I think there are two important points to keep in mind:
- A gimei sword can still be a piece of very fine craftsmanship.
- More importantly, this is your family treasure, and it was likely the treasured possession of a Japanese family decades ago as well.
Depending on the time, energy, and money you are willing to invest, you could certainly have the sword polished and have a new habaki and shirasaya made. Personally, I would not worry too much about the fittings, but again, this is entirely a personal decision.
In the end, it is completely up to you.