It's easy enough to do still, just needs a spot of silver to cover up the rim.
Is it just the photos, or is it the same in person? If the latter I'm sure you could add a little more when you're doing the possessed.
Different shifters as in a different one for each model, or a mix on them all? Either way I wouldn't say no!
The skulls are perhaps a little smoother, but there's nothing wrong with the shoulder. You might consider using the oils in future though?
I'll keep that in mind next time I've got a severed head lying around
The question is whether you can replicate the lens effect on an Astartes helmet. If so then I'll not be happy!