i have a 4ft tank (79g) and its fine for africans, but 6ft is better. and 8ft even better.. you get the idea
plenty of rockwork/hiding spots, as said previously change it all around if you have a bully.
peacocks arent usually aggressive, theyre the weaker/whimpier of the africans usually.
the biggest prob with adding fish to an established tank is that your new fish will always be bottom of the pecking order until they establish their place in the heirarchy.
you can try adding more fish at once so the aggression is dispersed amongst more "newby's" in your tank.
as for acclimation:
dont just float the bag and then up end it into your tank.
float bag for 10min, add a cup of your aquarium water to the bag. wait 5min. add another cup of water. wait another 5. then net your fish and add them.
dont add store water to your aquarium, just incase.
the idea is to slowly dilute the lfs water to be similar to your own so there is less of a PH change shocking your new fish.
they'll still get bullied by your boss, but they wont also be suffering from some degree of acclimation shock
while being bullied. (one less place of stress for em' )
if your boss has plenty of wimmin's to show interest in, it might help too.