The most recent update final cut pro 6.02 allows you to transcode on ingest from hdv to prores using firewire. yes/No?
I am sure it does, look at this page
http://www.apple.com/support/releasenotes/en/Final_Cut_Pro_6.0_rn/
so why not build an offline copy of the sequence, recapture using hdv to prores. surely this is quicker than any other method. maybe even use media manager to cut the unwanted footage
I agree about the card.
you would need the aja or blackmagic card for HD grading whatever but the capture can be done on any mac that supports final cut pro 6.02