Progress!
I bought a model in the style I wanted from a Japanese seller on eBay. The model is about 10cm tall (4").

I followed this tutorial on photogrammetry.
https://www.youtube.com/watch?v=1D0EhSi-vvc TL;DR: Take 100 photos from all angles and magic software makes a 3D model from them.
It took several attempts to get a working result. I had to cover his boots in cornflour to reduce reflections, and also his hair and pants because black doesn't seem to register well as a solid object. Here's the result:

He looks a bit chewed up, but hopefully I'll be able to smooth that out. The important thing is I have the right pose and proportions.
Thanks for those photos by the way Strange Wings. I couldn't use them in the end but I appreciate it.