I can't advise putting Cyprichromis leptosoma or any other Cyprichromis in a 2 foot cube, If you where after taking up that open space Paracyprichromis nigripinnis could be an option. you'll be suprised how much of a territory 1 male Brevis holds.Thank you for your suggestions.
The julidochromis transcriptus are a great looking fish!
I can see why you chose cyprichromis. They seem to offer great harmony with in the tank by hanging around the top half.
This will give a breather to the bevis.
As for the brevis Each pair will be positioned on opposite corners of the cube with a centre pillar of lava rock that will rise like a tower in the centre.
Considering their territories range i would not be surprised if they never see each other.