I assembled the area of the helmet in question. The fit is a little awkward but it goes together. The thing that bothers me more is that towards the back of the helmet there's these too edges are supposed to be connected but the shape doesn't match up so it kinda leads to this weird overhang.
Thank you to AceNat and Spacemeat for pointing out the couple flaws in the Kat helmet. It turned out a couple of verteces did not merge when I wanted them to so that issue has been dealt with. Although I'm not certain about that overlap part Spacemeat, I looked at my model and everything 'looks' fine. I'll keep checking it out though later on.
So here you are:
The redone Kat helmet
http://www.4shared.com/file/yE1-RmTf/Reach_Kat_helmet.html
Body Armor
http://www.4shared.com/file/RGyKCL2r/Reach_Chest.html
Spartan 'sized'
http://www.4shared.com/file/TsVdiB-S/reach_chest_sz.html
Thank you Iganderson for offering to lend your unfolding skills for this. I want to say I'm sorry for making the file really detailed though. lol. Hope it doesn't give you too much trouble. If anything needs fixing, let me know and I'll get on it.