The broken hub definitely adds a new dimension to things.
I have no experience with them but just remembered these (see link) from Vintage Auto Garage. All the pieces are also available individually as well. The Alternators are equipped with ball bearings to better handle the stress imposed by the fan. On their page is also a link to installation instructions. Good luck with however you decide to proceed.
https://www.vintageautogarage.com/19...p/333912vn.htm