I, too, own a 1989 SC. Mine came as a frame and fork, so you shouldn't concern yourself too much with "correct" parts. Put on what you want. Not sure what to do about the fork; as others have said, that might be a bit of a challenge. The original features the very distinctive chromed Cinelli sloping crown. Is this something that one could order from Cinelli? Have no idea.

Personally, I think it should be properly restored. It's an iconic frame that's pretty rare.