I decided to chop the scan so just his head and shoulders were visible using Fusion 360’s mesh editing tools.
I tried printing it upright originally, but it failed partway through:
The support material had come unstuck. Plus, I was worried that the face might be marred by the support material. So I changed approach and printed the bust on its back instead:
This worked really well! It did take about 12 hours though, but the final result is quite impressive:
The filament used is Ziro PLA Marble; pretty nice effect!