Being from the old school of thought where "components/parts have gotten better but frames have not", I would say nothing is untouchable or should I say un-updatable. Im sure some, or most, of you will say that this is blasphemy, but I THINK if you were to put high(er) end components on a nice vintage hand built Columbus Steel frame, you would have an awesome ride! I updated my 1985 Bianchi Superleggera with mid 90's Dura-Ace but that was because I couldnt pass on a unused full D/A gruppo, including seatpost for $200.

Unless youre trying to sell it, add and replace according to your taste and standard... hell the pros do it why shouldnt we??!