The preds I mentioned before. They aren't done, but this is just to show the parts swapping.
The one on the left is using all of the armor from the armored Borg/Lost Predator but on an AVP body. It's a little small, but not too noticeable. The predator on the right is AVP Celtic's body, Scar's unmasked head (chopped) and Vipers mask glued in place.
The removable predator masks work perfectly since they have to be made bigger to accommodate the predators face.