Firstly, I would advise not to combine these cichlids.
Heros severum comes from the Amazon drainage, and requires therefore soft, acid, warm (27 C, 80 F) water. The port acara (I think you mean Cichlasoma portalegrensis with that) dislikes this warm watrer
Jack dempsey need hard water, cooming from the Yucatan penninsula of Mexico. The soil there is chalkey
Synspilum comes form that same area, but texas does not. The water would be OK, but the temp is too hot. Porte Alegre and the north of Mexico are appoximately as far from the equator
The jewel, hemnichromis cf bimaculatus is from west-africa, requiring water of the same kind as Heros does, but these fishes are VERY agressive. I never heard of anyone keeping them wsuccesfully with other species of cichlids
Further, a rio 300 - I think the tank contains 300 liter of water, being slightly smaller than 130 * 50 * 50 (that is 325 liters)is too small for almost all these fishes. A pair of Jacks, and no more, the same for the acara and Heros. Hemichriomis may be kept smaller, but texas grows to 25 cm, synspilum even larger.
Finally, a pleco.
As the tank is far too small for Pterocgoblichthys gibbyceps or pardalis, the most obvious choise would be the common Ancistrus cf cirrhosus. Personally I was lucky to find Pterogoblichthys sp cf punctatus, getting only half as large as Pt gibbyceps.
I wo8ld not choose any of the fancy L numbers, myself - unless combined with Heros in soft, acid warm water
In my experience, texas water is similar to that you describe from Mexico - hard, alkaline and fairly cool (around 20'C year-round-average, but obviously it would be hotter during summer and cooler in the winter)
And yes, that's far too many large and aggressive cichlids to keep in one tank.
Interests: African catfishes and oddballs, Madagascar cichlids; stoner doom and heavy rock; old school choppers and riding them, fantasy novels, travelling and diving in the tropics and all things nature.
yes, you should choose and keep some trade the rest
IMO you could keep a pair of Jacks in there with a pleco.
Ancistrus is a good choice, one of the smaller Hypostomus species would work as well.
Hypostomus doesn't get as large as Pterygoplichthys and they have a lot of character wich is a pro in a cichlid tank.