Even in ideal conditions the oil in the shock has been in contact with those seals for a very long time. In a perfect world that shouldn't soften or deteriorate the seals, but there's a good chance of that. They weren't designed with that kind of operational, or shelf life, in mind. Of course, neither was anything else on these cars, and they're still around. ;-) I would keep a close eye on them if you do use them. They may work fine, or they might blow the seals out on the first pothole.
For a street/strip set up the RCD Bilsteins probably aren't the best choice. They were intended more for handling, not straight line stuff. And the lengths are generally for lowered cars, or at least nothing higher than stock, so they may not be long enough if your car sits high in the back.
