As an experiment, try being massively aggressive with your EQ cutting.. Get your 808 kick and set your high shelf gain to the maximum reduction value.. Now, sweep the frequency down until you hear the kick sound starting to have the high frequencies removed.
Now, do the opposite with your bassline.. Set your low shelf gain to the maximum reduction value and sweep the frequency up until you hear the low end in your bassline being cut..
You now know the ranges of the two. Hopefully they will not overlap but if they do you will need to be more aggressive with your cutting.. Take more high end off the kick until you start to lose the fundamental part of its character.. Take more low end off your bassline until you start to effect its character..
Too many times in this forum I read 'EQ!! Boost everything' in answer to peoples 'I need more bass' questions. Applying EQ boost is one easy way to reduce the perceived low end your tracks.. The number one rule for EQ especially for us non-experts is 'never boost, always cut'.. Okay, perhaps very rarely boost
Let us know how you get on..