(LAME encoder - VBR) What are the 1-9 equivalent to the "Very Low" - "Very High" settings?

My general question is this one: according to the lame encoder documentation, there is a total of 9 different VBR quality settings (1-9), but there are only 6 options in Soundconverter, ranging from very low to extremely high. To which LAME 1-9 settings is each of them equivalent?

I have a second question, in direct relation to the first one. For my needs, I find that "normal" is too low and "high" results in big files, so I was hoping that lame V3 or V4 would be a good compromise between the 2, but it doesn't look like these seetings are available in Soundconverter. Is there a way to force Soundconverter to apply VBR settings that are not part of the basic options ?

Thank you very much (answer can come in French or English BTW).