my thought (not that it's worth anything) is that anything that makes the bike
usable (i.e. cables replaced) will not detract from the value (albeit if the replacement
is either period correct or exact replacement).
I wouldn't mess with the spokes, other than to clean them up with something like mothers.
other than that, maybe (and its a big maybe) tires if the originals are dry rotted.
Remember, it's only original once.
marty