Because Geophagines are most comfortable in groups of 4 or more, if it were me, I'd keep all the Geos and only get a mid water column living fish.
Since Thorichthys are the Central American equivalent to Geophagus, they would not be my first choice, as they would see each other as competitors.
And because a 90 gal is really not very large, I would think a shoal of smaller fish would be a better choice, than a large cichlid.
And as stated above, any vegetarian Uaru, or Vieja/Paratheraps or omnivorous Herichthyines types would tend to destroy your plants, or best case scenario, up root them.
If you must have cichlids, I agree with the above, that the geographically correct discus, or even angels would be more apropos.