Have you tried linishing the legs yourself, and polishing ? You do need a pedestal-mounted bench grinder fitted with polishing mops for this, but it is entirely possible to do this job yourself, as long as the pitting is minor, and not in the region where the fork seals move over.
Most of the old z650 fork legs I have seen in the past have some sort of pitting, but usually located up the fork leg near the lower triple clamp....you can clean this up pretty well, rotate the forks around a bit and 'bingo' instant better view !
If the pitting is deep, then the legs need to have all the plating removed, and re-plated. You could talk to any local plating service to see if they can do the job.....it's not hugely difficult.
