Hi Doug183,
It should be.
That said, assuming you want to use zfs, it might be better to find a plain old "dumb" HBA that you can connect the storage chassis to and sell the RAID card. ZFS is happiest when it has direct control of the disks, with the 8888 card you might have to make each disk it's own RAID-0 volume & prsent it to FreeNAS that way. You would be much better off converting the controller into some more RAM.
-Will