I've looked into them as a possible next project myself Slammer...
Like JOHNO said, ALL Yugoslavian barrels have "Dark Bores". I'm told this is a result of the use of corrosive Yugo Ammo. I've chatted with several Yugo owners and from what I've learned getting a Yugo kit can be a total crap-shoot as far as the barrels go. Some kits come with barrels that are so corroded that a cleaning patch can't be run through it, while others have told me that their barrels weren't that bad at all: sharp rifling with just a small amount of pitting in them.
Is buying a Yugo kit a good idea? It's totally up to you. If it's a Yugo AK you want, I'd suggest buying a complete gun instead of a kit. I think Red Star Arms builds Yugo's and they offer a one year warranty on them if I remember correctly. At least you know the barrel is a clean one.
I have also seen Yugo front ends for sale at FTF Industries for something like $50.00. (Barrel, Trunion, Furniature, Gas tube, Front Sight, everything).
http://www.gunbroker.com/Auction/ViewItem.asp?Item=38315059
Alot cheaper than getting a full parts set and ideal for building a Frankenstein AK. What are the Yugo kits going for now? $150.00 - $175.00? You could buy a Romy Kit & Yugo Front end for around that much and end up with a pretty cool gun.