Going forward as we move to Polaris as a codebase, under no circumstances should anyone make a Pull Request changing the stock Space Station 13/Polaris Station sprite files. The ones that we are modifying are suffixed with _vr.dmi.
They will be located in the same folder as their non-vorestation sprite files. So you might see species.dmi and species_vr.dmi. You want the _vr one. If you need to modify something like species.dmi and there isn't a species_vr.dmi, speak to a developer. If you are a developer, speak to a different developer.