A few "mights" and a couple of "wills" to consider:
A 75gal
MIGHT work for just one d. compressiceps (though as previously mentioned a 6ft is optimal), 75gal too small for two of them, though. Here's a pic of one of my eye biters among some
5-inch blue dolphins (and the d. comp has grown since this pic):
They
MIGHT get along ok with yellow labs.
The socolofi's
MIGHT make it rough for them (it's ideal to add more aggressive species to an established tank than less aggressive one's, established socolofi's
WILL have the upper hand).
Any fry and small (< 1.5") mbuna juvies
WILL be at jeopardy when the eye biter grows larger (in the wild they eat mbuna fry and juvies for a living).
Nothing is really certain in this hobby so even if you did add 1m/1f, things
MIGHT work out.