Hey guys i was looking for a good barrel and was wonder what was a good choice, i have heard good things about green mountain but was hoping to get some input. I have also been looking for a good quality under folder kit for a milled receiver and was wondering if anyone could point me in the right direction.

Given the current price of Type 3 barrels from K-var that's what I would go with. Not because they're superior (they're not), but solely because they're made by a military arsenal. Also, given the underfolder kit you'll find will be Bulgarian, I like to have as many Bulgarian parts as possible to maintain "correctness". Once those barrels finally sell out again I would go with an AK-Builder barrel as they've been the most accurate I've ever used.
http://www.k-var.com/shop/AK-332CL.html

Im actually working on a milled rifle myself right now. Was originally going to do an underfolder but changed my mind and decided to go for a fixed stock instead.

I got my Bulgarian underfolder kit from What a Country.

http://whatacountry.com/bulgarian-ak-47-milled-underfolder-parts-kit.aspx

Bought 2. One was almost perfect finish and all numbers matching. This will go to the current build.
The other is quite a bit more used looking and only the main components match. That will be modified to build an airsoft clone of the real AK im building.

Using Tortort receivers for both. And an AK builder chromed barrel.

Since I changed my mind about the underfolder. I actually have 2 Tortort UF 80% receivers I can let go for cheap if you want. And 2 bulgarian stock assemblies.