It won't work, the whole barrel assembly is different. I'm sorry but you'll have to do the WE G39 conversion on it's own. And you'll have to buy a proper G36C AEG.
The G39 uses a design close to real steel. You can see the barrel nut, the gas tube and gas block. The barrel is a piece on it's own.
The AEG uses a whole barrel assembly with fixations that screw into the body.
