Gonna toss this here because, frankly, you're in the wrong armor class for Space Marines. We can find stuff to make some crude approximations, though. It'll probably look closer to a Reiver than anything else, or even a Scout, but nothing will come close to an actual marine. Refer to the link above for the following pieces:

Boots: Magitech Gloves: Forgeman Shoulders: Foregman Leggings: Studded or Council Watch Chest:Glorious Helm: I think you're hooped, here. Priory is probably closest to a Reiver. Forgeman if you're desperate and have a good imagination. Gas Mask if you're ok straying on the helmet.