Matt, I'm glad that you got a refund on those bearings from NY.
The bearings for 4200s are the same as Ferrari 360/ 430 and are interchangeable and still available. I've never worked on a GT/QP, but could someone check and see if the hub carrier bolt pattern is the same? If so, use a 4200/ Ferrari F430 hub with a wheel adapter to go from 5x108 pcd to 5x 114.3.
And no, there is no way to remanufacture the hub.
Spent last weekend rebuilding an engine for a friend, another guy there is restoring a 356c, and he was telling me that
every part is available from Porsche.
Maserati makes it SO hard to love our cars.