If you get some info before hand not really any different than working on any old bike. Unless your funds are unlimited it is just as hard chasing Campy parts. Now if you are going the hodgepodge frankenbike way then it might be tougher. It could be worse. The Swedish Crescent I am bringing back to life is full Nuovo Record with French threads! (At least that is what I have read)

By the way, anybody priced any old Campy Record 120 hubs lately? At least you can afford to buy most of the french parts. The Crescent will be shod with Pelissier Pro hubs for now because the Campy hubs are like gold!