For those who might be interested, I have a really nifty little interactive tool at toontitan.com that allows you to view the various mouth sprites needed for a character. Just click button at the top of the article on Mouth sprites. Once its open you can click the frames and it will show you a representation of the mouths to use.
Check it out at: https://toontitan.com/kb/g2-character-mouth-chart.html

I often find myself using it when developing new characters, i just open it on the side as I draw the mouths for the new character.