Hi, Leo:
Unfortunately no one with any G60 model that has installed W8 has been able to get the audio to work, no matter what they have tried.
I consider myself pretty good at finding drivers to work under unusual circumstances, and I have tried every relevant driver and trick I know of to help dozens of folks and nothing I have tried or they have tried, has worked.
Raise the white flag of surrender and reinstall W7.
A g6 is not a G60. Different hardware and audio chips.
Here is a link to many threads regarding this matter.