The bearings are used on most Maseratis from the late 1960s onwards. I don't have the numbers on the outer shells and inner racers. Maseratinet.com sells them for sure.
I did replace the rear ones in the past. I gave the numbers on the inner and outer bearing to a supplier here in Amsterdam and they ordered them for me from Timken. Same story for the seals. A local supplier had them on stock.
That broken bleed screw is always painfull! One of those live and learn experiences I guess. Believe me, I have been there!
Now, when working on dodgy callipers, I always start with applying heat to the bleed screw and making shure it frees up.