You would be far better getting either transcriptus, or ornatus in my opinion. If the multifasciatus are adults, established and breeding, the dickfeldi would be worth a shot, but not if the multi's are juveniles. Another option that could work for you would be Telmatochromis vittatus.
ya i actually mixed shellies and julies quite well.. in my 30g long.. 3ft long by who knows anyways they do just fine.. i put a little bit of lace rock in there for them and the rest is empty sand for the ocellatus.. as they get more aggressive towards each other i just move physical barriers between.. large empty shells.. single stones. bamboo chutes.. it has worked thus far with no ill effects.. one of my transcriptus even thinks its a shellie.. he hangs out around em and they pretty much show no aggression (interspecies-wise) cept for the domiant occie.. but yeah..hes a punk anyways good luck.. just remember dont overpopulate.. i only have 5 occies 5 transcriptus.. might get more to sex em and then ditch excesss males..