Thanks Garry,
is there an advantageous camera position do you think? Level with eyes, nose or chin? or will it not matter?
As Garry says, photography doesn’t really do recipes (paraphrased).
An example of a similar problem I had before.
Whilst I was a camera for hire I got an enquiry to shoot a ‘passport photo’, I explained that they could get one from a booth and that to hire me would be a full priced portrait sitting. The guy was quite insistent, explained it was for a Canadian visa, they were very picky and that they’d already tried a photo from a booth and a pro photographer and both had been refused by the Canadians.
So off I went to see them, and was greeted by a lovely older lady.
Here’s the problem: in her younger years she wouldn’t have had much of a defined chin, and time had not been kind to her jawline. So when the quality checks were done on her regular passport photo, it would have been impossible to measure from her chin to the top of her head. The normal clamshell arrangement for passport photos would be useless (creating shadow free light of her face and neck). I used a black reflector instead of white at the bottom of the clamshell, helping to give a shadow, and therefore a line that could be measured from.
There’s no recipe, or even guidance as to what to do in that situation, but simply looking at her face, I could see immediately the problem (no one had told the couple why the photos were rejected), and the solution became quite straightforward.
We ‘see’ things that non photographers don’t, when I handed over the images, they weren’t convinced that what they were looking at was ‘different’ to what they’d already sent, but rather than pointing out the ‘fault’ I simply offered a free reshoot if the images were rejected (fairly confident it wouldn’t happen).
So we gather knowledge of the physics, and experience of real world problems and solutions, and next time we’re behind the camera, we can see more clearly.
My gut says shoot at the eyeline, but I can’t see your model and some faces suit a lower viewpoint and some higher, only you can see that when you’re shooting.