Hi Matt
The Nexus 6004 has a expansion module, which supports native FC as well as FCoE.
N6004X-M20UP
Nexus 6004EF Chassis Module 20P 10GE Eth/FCoE OR 8/4/2G FC
The interop matrix
http://www.cisco.com/c/en/us/td/docs/switches/datacenter/mds9000/interoperability/matrix/intmatrx/Matrix1.html
shows SVC and IBM Storwize 7000 support.
Nevertheless I would check the IBM interop matrix
IBM—visit http://www-03.ibm.com/systems/support/storage/ssic/interoperability.wss
Walter.
PS. I did many implementations with Nexus 5k as a storage switch, or hybrid Ethernet and native FC.