I can't remember now what I did with the lattice but I had an asymmetrical head when looking in front view.
So when I deleted half the head and mirrored it, it no longer matched with the previous head. I didn't think this was an issue but when trying to shrinkwrap the new head with eye sockets to the old head 'head normals' doesn't work properly. Not sure how best to fix this without removing/redoing the head lattice and starting the eye sockets again - any suggestions?
With eye sockets before shrink wrap
After shrink wrap
Update. I *think* the head normals moved up along the z when I copied it. So I moved it down by eye and now things look better.
I do however have stretching of the eye sockets from the side - is this correct?
I do still have this artefact from the asymmetry tho which annoys me
[ack! can't upload this image as only have the 'image URL' option]
There's not a straight up answer, it depends on how you have things set up. What I do when I get into these types of situation is backtrack a bit, get things to their default state. I would remove the lattice influence, maybe delete it and add a new shinny one, straighten the head, align those vertices, etc, just so everything is back to default. Then I start again taking one thing at a time watching that it doesn't break again, and if it does, no I can focus on solving that sole problem, which is easer, then move on.