My initial thoughts are that the texture of the cylinder head might not matter as much as I like to believe. Perhaps polishing and smoothing the combustion chamber doesn't matter either? I wonder what shapes they'll carve in their heads next?
I remember (easily wrong as its 26 years ago) that the early eighties Mercedes diesels (prechamber type) had grooves radiating around the cylinder head circumfirentially around the prechamber. Similar to the petals of a chrysanthimum.
Can't remember the number, but the first time I read about Singh's experimentation (Pop Sci or PM) I thought about those grooves. Thinks the year was 1982. Seemed to help with diesel knock.