while wasting my time surfing the net, some days ago i saw some amazing stuff on westwindproductions.co.uk, the mighty separate head system: speaking simply it is a set of separate heads witch allows you to customize greatly your plastic imperial guard... i think they fit perfectly cadians. check 'em out!
personally, i'm gonna catch them to recreate the old stormtroopers (the ones from 2nd edition, remember?)... i bet it will work out! also, if you wanna recreate some sort of krieg trenchmen, you should exploit the nice heads with gasmasks... let me think what do you think about it, cheers!