I'm building a nice RecordAce frame and have run into an issue with the top tube brake cable braze-ons. They seem to be cable guides but are too narrow for the cable housing. I've built a couple bikes with something similar on the chain stay just in front of the rear derailleur. In that case I've used a ferrule that fits the derailleur housing but narrows on the other end to fit the braze-on. They were spares from some DA bar end shifter kits. I need something similar for brake housing.
I hope someone can tell me the correct terminology or a source for such a part.