I tried to pop a black endor rebel head on the body to take a shot at ICMG but the neck post ball joint is too small on the Naboo solider.
There's always a way. 
Yes, yes there is. When I'm customizing and this happens to me, i use wirecutters to get the neck post ball joint off of one body, krazy glue it on to the other, and pop the head on. works like a charm

. some of my creations will probably be on thecustomalliance in a matter of weeks just sent them to curto.