Target and initiator HBA cards should be the same part - whether ONTAP sees them as target or initiator is a software config change via fcadmin config. The man page says "not all adapters are configurable by this utility" - maybe you've got one of these?
Assigns a new WWPN to an adapter. You must offline and then online the adpter using the fcp config command before and after changing its WWPN. The WWPN must be one of the valid and unused WWPNs displayed by the fcp portname show -v command. The original WWPN of this adapter is reset to be unused. This command only applies to local Fibre Channel target adapters in standby or single_image cfmode.