totally understand mate, no offence meant in anyway. just going by my own brief but steep learning curve.
one of the parts i love most about cichlids is also one of the hardest to get right, that you can get a bunch of cichlids all brothers and sisters hatched at the same time, one will be the best, friendliest fish you'll ever own. another can be a complete and utter jerk.
they all have their own little personalities

but it can make choices hard as peoples experiences will vary.
i couldnt tell you exactly what will work with what, im honest enough to admit i dont have that experience. i can only advise on whats worked for me or
lfs display tanks ive seen
what i do though is check
the cichlid-forum profiles page to get an idea of what im buying.
it sounds like your going with a lake malawi tank, so i'd try stick with fish from that location only. (i learnt the hard way

)
it tells you things like full grown size, aggression, etc.
ive used it to rule out a few fish in the past
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(4ft) 79g / 285L AquaGrande 120 main tank
(4ft) 52g / 192L Fry/brooding tank
(2ft) 19g/ 75L Fry/brooding tank
theyre fully cich'lid, bro!