To put it in perspective, Ermz (Ermin) from this forum said somewhere, IIRC, he uses a high pass filter set anywhere from 80Hz to 150Hz and I don't mean this in anyway to kiss his ass, but from an objective standpoint, I've yet to hear a larger and better sounding mix from anyone else on this forum (not including Sneap btw).
I'm not convinced you really there is a need to set the high pass filter any lower than 80-90Hz really.
I'd just set the HP filter anywhere including and above 80Hz and make sure the tone is just tracked well, so you get a good source tone.
"Mid bass" as they call it, seems to lie in the frequencies of 90-150Hz, so I think it's safe to say guitars still have bass in them, but it's just that all or at least almost all, the sub bass is filtered out of the sound as to make way for the bass guitar and kick drums.
But really, as obvious as it might sound, you need to concentrate on getting the guitars to just sound as good as possible within the mid range spectrum, and then worry about dealing with any excess shit that falls outside that frequency later with high/low pass filtering, multiband compression etc etc.
It's all about getting a decent separation in the mix. Guitars sound too big, they fuck with your mix, they sound too little, they fuck with your mix. Just like anything in this audio engineering realm, it's all about striving to reach the best balance possible.