Since it appears that Campagnolo (along with just about every other maker out there) has given up completely on making front derailleurs for the classic 28.6 (1") tube size I am left with one of two options:
1) When I have my frame painted have them add a braze-on for a braze-on derailleur ($30 charge)
pluses: will be able to use any braze on derailleur easily. no need for adapter for the new style derailleur. won't screw up the paint with a clamp.
negatives: won't be able to go back to an older clamp derailleur in future if I rebuild with period parts.
2) Find a good looking derailleur adapter clamp.
pluses: won't lock me into braze-on style derailleurs on this frame.
negatives: haven't found one yet I wouldn't mind clamping to my Gazelle after it gets a fresh coat of paint and start installing a Campy Chorus 10sp group on it.
I've looked at the clamp on adapters that Nashbar carries (at least they've got them in silver, but yuck-o cheap-o looking still). And I saw one at biketiresdirect.com (I think it was them) that looked like a small step up. And I saw the Campagnolo ones, which started at like 30.x something like that. ie: bigger than my tube.
Opinions, options I've over looked?