Headset bearings are proprietary items and not available in the general bearing market, so don't bother searching there. You will have to find an FSA dealer to get you that one. I would find one on the FSA website, if they have a Distributors/Retailers section.
Headset bearings are fraught with difficulty because no-one has adopted a standard. The problem is that there are several plermutations to play with.
ID, OD, inner chamfer angle, outer chamfer angle, height and non-chamfered raise.
Even to the trained eye this is sometimes problematic to try and match two bearings.
FSA makes a special bearing tool (2-piece actually) that can measure inner and outer angles but even that tool sometimes left me stumped. It is easy to both the measurement because it doesn't keep the bearing stable whilst measuring.
It's been a while since I've done this but the code you have doesn't look familiar. FSA had product codes laser etched on the side of the bearing, IIRC. That may be more helpful.
