I have a version of the female Guyver armor that I was able to "seat" a head on it and turn the helmet off.  To be technical, there are 3 versions of the original Powersuit, the standard, the Varia, and the Gravity, all the same but different colors.  Then there's slightly different versions, some with really big shoulders, some without, and then there's the Fusion suit which I'm guessing could be some kind of bio armor like the Guyver

So, the question becomes, how many do you want and can you get someone to build 'em all? :P