It will probably work for a while, until it, or the others hit maturity, in a 300 gallon, you'd have the best chance after maturity.
I had a pair of tetracanthus do well until maturity, and spawning occurred in a 6 ft tank, but at that time, all others had to be removed to save the other cichlids lives.

One other thought, I find when you try to keep cichlids together that look similar, (color, body shape, mouth shape) like any Parachromis with Nandopsis, they tend to see each other as either competitors, or if you have different genders, a partner to hybridize with, both scenarios not a good idea in my book.
You often have a better chance at a community in a large tank, using cichlids diametrically opposed in appearance, and feeding styles, which usually means, non of the same genus in a tank, which is often the case in nature.
You would hardly ever find 2 of the same genus in a habitat. One usually forces one or the other out.