I wonder about lyonsi breeding. I would imagine all are now from the same line without any fresh blood coming in.
Agro wise I would imagine they're still pretty bad in a tight area being an amphilophus. I would try a pair in a 75, but be prepared to get a 120-125. A chunky 10-12" fish will dwarf a 4ft tank quick, but I would imagine you would have awhile.