VFC HK416 parts compatibility (replacing 10.5" barrel with 14.5")

[NAAZ]

so I'm looking to buy the VFC HK416 D14.5RS GBB.

I would prefer to have the Asia Edition and the 2015 ver.

on RedWolfAirsoft, the product listed is what I assume to be the D10.5RS:
http://www.redwolfairsoft.com/redwol...ia_Edition.htm

so to replace the stock outer barrel 10.5" barrel with a 14.5", I'm going to get the Z-Parts CNC Steel Outer Barrel (402mm):
http://www.redwolfairsoft.com/redwol...FC_M27_GBB.htm

I'm not an airsoft tech, so I would like to know if I need anything else to make the assembly work. I'm not able to find any 14.5" inner barrels, but I'm okay with that because I'm building the project gun for collection and aesthetics, not really for field performance.

edit: someone mentioned elsewhere that the specific product that I linked comes with a barrel extension for the 10.5 to become 14.5. can anyone confirm?