Thanks to Mustang Dave for finding it, and of course Adam Beamish who modelled this awesome bust in the first place. I took it into Blender (zbrush is just frustrating me at the moment...) and increased the subdivision on it and then had a go at resculpting the lost features. I plan on printing this out really big so I'd prefer to avoid the sanding. Yes the file size is increased significantly (36x..) but so does the quality of the printed output. The plan was not to change the original mesh, it was great to start with - so I didn't add anything much besides the spike liners on the shoulders and added muscles on the back/front, and gave him some definition.
The reason I do this is simply to avoid square edge prints and try and have the printer always printing round fluid shapes, as the Flashforge tends to prefer clean round shapes than low resolution round shapes that have low vertex counts. I understand the want and need for small meshes that are good quality, and Panthro was a great example of that, but there also seems to be a demand for hi resolution models to print - and after a couple of years I am truly over sanding my prints, the closer to finished I can get when it prints the better. Slicing big meshes is not scary! :p