The 1000 rear shock apparently fits with some modifications. Although it's not a brill shock by modern standards its better than the standard 600's unit, with preload, rebound and compression adjustment. It's also rebuildable, unlike the 600 (unless you fit a Schrader valve).
Still waiting on Bwizz to confirm R6 shock fitment to the 600, and it's still an unknown whether the spring & damping characteristics will suit a bike 20kg lighter. Remember, an R6 shock fitted to the 1000 uses the 1000's shock linkage ratio....the 600 *might* be quite different
Besides, the problem with chasing R6 shocks is that of demand.... you will be competing with R6 owners and Fazer 1000 owners for the units. Whereas you will compete against no-one for Fazer 1000 shocks on ebay (and so should be dirt cheap)