Graven Images comparison size?

[Katsuhiko JiNNai]

I yet know that the Graven Images miniatures are bigger (40mm), but that's not a big problem, because I need three miniatures from the range that must be bigger.
I only must be sure about one miniature, the levitating officer:

I want to cut the head and include a plastic Warzone Imperial head (the plastic officer head from the old WZ base box, if somebody remember). The plastic head seem yet big, but it's big enoug for the levitating officer? Thanks.