So you basicly want this? Only the helmet and probably all open edges etc merged so it doesnt gives any problem in pep? i'm friendly today here... I even edited the texture more to the real model.
If you open it in pep just hit the textures and load normaltexture...
this looks really cool, but it needs to be smoothed out a lot more, since its meant to be a tight helmet, it would take too much after work and a bigger size to make it look nice