a few options seem possible. one is that Diskwarrior has a great reputation for mounting and repairing damaged disks.
on the other hand, if you are sure you have all your needed and irreplacable files on your FW drive, then there doesn't seem to be much reason you couldn't just reformat the original and use carbon copy cloner to move it all back.
either operation is probably going to take awhile, so it's pretty much your choice. just be sure you've learned your lesson with nortons which will claim to be fixing something from now untill eternity.
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