Cool is your friend
I have a 1985 635. Love it, but was discouraged from buying a 633 from this forum. But since I bought mine, I've noticed that the coolest interior and exterior color combos were available on the 633. If the interior you've found has an unusual color like that caramel (not the beige: darker) or the dark blue, or if you can find an exterior that has some of the soft pastel colors, I think those will be valuable later because you just don't see them that much.