Jim, "typically" One off, is used in reference to a custom, "one of a kind" = One off. And then restoration is another meaning all together as you know... so "typically" the two would be contradictory terms, and you would not uses them in the same reference.

So perhaps it would be used to describe a vehicle that is a one of a kind custom done say in the 60's such as a Big Daddy Kustom, that has been restored to the way Big Daddy customized it in the day?

Where did you hear the terms used together? I've heard many miss used phrases from the announcers of the Barret Jackson Auctions... they at times kind of make things up on the fly! Lol...

Brett!