I hate to keep being a nag, but I shall ask, as it's hard to tell... is this the one you're looking for?
http://brashsculptor.deviantart.com/art/Halo-Wars-helmet-WIP-165227534
If it is, you can probably contact her for the file..
If that is not it, then you may be out of luck. There was work on the set here, but it sort of petered out without finishing. I have what was finished of that set, which seems to be the chest, forearms, shoulders, shins and biceps, with partially finished codpiece. I really hope that deviantArt one is the right one.