Since you mentioned that "This cluster actually used to be running Solaris 10, using different disks on the SAN", its not clear to me if this cluster was a failover cluster configuration or it was a parallel (CVM/CS) configuration. If it was a parallel cluster configuration and if you saved away a copy of vxexplorer outout, you should be able to review the saved vcs configuration (main.cf) as well as some vxvm output. You should be then able to use these info as a "template" to rebuild the cluster with cvm/cfs. If it was a failover cluster, you then need to follow the user guide emailed to build up cvm/cfs.
here is another technote for your reference https://sort.veritas.com/public/documents/sf/5.0/aix/html/sf_rac_install/sfrac_ora9i_add_rem_nd8.html
although it was prepared for an old version (5.0 for RAC cluster) for AIX, the setps involved are the same