VHS Hi-fi audio is probably about 6-8 bit depth quality and that’s your limiting factor.
That said, if I was archiving, I’d encode to PCM audio, because the source is high quality analog and PCM is lossless. You would get everything you could out of it.
If space is a concern, you won’t be disappointed by 256-320kbps AC3.
I rarely would consider 192kbps for high quality digital sources.