I guess i am confused on what you mean implement vstorage. Are you talking about reformatting it to a VMFS datastore?
If so, I would take option 1 and do a cold migration onto the new storage and then reformat VMFS. Honestly, you odn't even need to add it into the new cluster, just right click and cold migrate the VM's once in Vcenter. Just add it to the datacenter and not the cluster.