Right now, I'm building a mid-80's BMZ Columbus SL tubed Italian frameset with 10 speed Campagnolo.

For me, it's pretty much mix and match to get the bike I want to ride. There are exceptions that I would keep all original, but in general I've no problem with building any way that suits my fancy.

It's not like I'm doing any permanent damage - shaving off braze-ons and so forth. And most vintage bikes have been tinkered with and changed around long before I got my hands on them. Many of the higher end bikes of yesteryear were ordered as framesets and built to customer spec, so who's to say what is "original", anyway? Granted, modern drivetrains on vintage frames are obviously not "correct", but the idea of mating old and new doesn't bother me much.