I've been conflicted about this question several times before. I would buy a very nice all-original steel frame bike, then think about upgrading the components. My conclusion has always been, if the bike worked fine with its' original components, why mess with the designer's intent. I also feel that putting modern components on a vintage bike would subtract from, not add to, the value of the bike. I'm picking up an 83 Trek 560 today and have a 10 spd brifter group that I'm considering putting on it. But, would this upgrade turn-off a vintage bike collector if I ever decided to sell it?