Don't get the Iron Warriors shoulderpads, bro!
They completely suck. They are not that well cast, and they look awful no matter how well you paint them. If you have your heart set on them, I'd be happy to sell you mine for half whatever
GWS wants plus postage - that's right, I paid for them, had them delivered, and chose not to use them. Scalewise, they do match, though.
I wound up using regular old
CSM pads for mine, and occasionally, a loyalist pad or two. I also used some Maxmini heads, and
GWS Iron Warrior torsos - those are really nice, and I recommend them quite a bit. Here are some (zoomable) images from the gallery from when they were in progress - I've cleaned them up a bit since then, but you get the idea.