This guide shows you, how to obtain a corpse with 19 white skulls. All you need is the latest DLC (Better Save Soul), because only then it is possible to manipulate and upgrade organs. If you dont have it, that means you can only get 16 white skulls.
2) Organs out
Now you should have 0 of both skulls.
3) Organs in
It does not matter which organ has which quality. It only matters that each one has one of the qualitys from above. Each quality can only be used once. For example:
The Heart with (1), the Brain with (2) and the Intestine with (3).
Place them inside and you shouls have 4 red Skulls and 9 white Skulls.
4) Enbalming
5) Blood and fat
6) Last step
Just the white skulls. Dont bring additional red skulls to the skin or the flesh. Bring the organs back in to the corpse and you are finished. You shouls have 0 red skulls and 19 white skulls. However you can only use 16 white skulls efficiently on the graveyard, so its up to you if you want to do it but maybe in the next DLC there could be a gravestone which is better than our current ones.
Thanks to MCMeview for his great guide, all credit to his effort. you can also read the original guide from Steam Community. enjoy the game.