For a 75gl tank of Tanganyikans that would feature N. leleupi I would stick to fish that could hold their own with N. leleupi.
The Cyathopharynx are not too aggressive, their issues lie in territory and dominance. they require large tanks for their active habits, large nests and are usually kept in species tanks as they are easily outranked and subdominant featherfins never show off their full splendor.
With leleupi in a 75gl tank I would opt for a second rockdweller, one of the larger Julies and none smaller than dickfeldi which means dickfeldi, marlieri (no dwarf forms) and regani. Chalinochromis sp. would also hold their own as they can also be quite territorial.
I'd be weary of keeping shelldwellers with leleupi since leleupi are reputed to be accomplished shell predators. The vitattus, though spunky and charming, are long and thin and females could easily fit in an adult leleupi's mouth. IME they're not aggressive enough to hold their own. Lamprologus ocellatus on the other hand, might just prove bulldoggy enough to stand their ground. Unlike my vitattus, my occies never hesitated to attack my hand when it entered their water, unlike the vits who duck for cover.
With Tropheus sp. you have a difference in food requirements and are thus incompatible with the more omnivorous/piscivorous/planktivorous/carnivorous/insectivorous lamprologines you are looking into.
I would consider any fairy type (N. brichardi, pulcher, splendens, gracilis, savoryi, marunguensis) carefully. They can turn increasingly aggressive as their population grows, and it grows quickly(!) and slowly take over the aquarium with their increasing numbers. Some tankmates can keep fry numbers in check. For this some folks often employ some Altolamprologus or torpedo shaped fry predator. They hang around the colony's territory and snatch up fry wherever they can. For some folks even this is not enough and have to opt for periodical tear-downs of the aquarium to clear out excess fairy's and keep the colony numbers (and aggression) in check.
As for Cyps, I think some Utinta's would be very nice a group of about 12-14 is fair, weeding out extra males as the pop up and replacing them with females.
A 75 with two pairs of rockdwellers (at opposite ends) and a shoal of Cyps for the open area in between IMO would be perfect.
