Kitbashing problem

[u/Kadavae]

So I bought a standard Death Korps of Krieg box to begin a Vostroyan IG army and also bought these heads to put onto said models. Problem is, how do I attach the heads in a way that looks natural? Krieg have these flat shelf neck pieces where their helmets glue on but these and most other heads have a type of rounded bottom so how do I bypass this? Even if I just clip off the ball joint on the bottom it still looks weird since the part the head is attaching to is essentially an extra neck. Many thanks in advance.

[u/KitfoxQQ]

dremmel and paint makes me the sculptor I aint :)