I tried what I could find online but it's not being recognised. I had the same with another set of wheels (cross trail) and even contacting Mavic resulted in them saying they had no idea what the wheel was using the serial on the rim.
Serial number doesn't show anything.
I've got a longer spoke, but it's 307mm - but it may well snug down better if it's the right one.
Also here's a shimano fhb might be ok -
Bearing hole is around 8mm
£15 the pair posted