In principle single hba / target zoning, for obvious reasons.
But you are using a DS-6520B, so you should be able to upgrade to FOS 7.4. And FOS 7.4 can use "peer zones". these are zones, with single initiator / multiple targets. This is all described on page 351 of the FOS 7.4 Administrator guide, downloadable from the EMC support site.
Peer Zoning allows a "principal" device to communicate with the rest of the devices in the zone. The
principal device manages a Peer Zone. Other "non-principal" devices in the zone can communicate with
the principal device only; they cannot communicate with each other.
This will give you easier zoning and less RSCN, to the other devices in the zones.
I believe this is your best option.