Size is no problem, I haven't measured it but it is huge. I'm currently working on my Asian tank, which is 500 litres, and the Amazon tank is about the same.
LOL Pacu's get up to 3 feet long, very deep, and very LARGE. Necessary minimal tank size, around 600g when full grown (for one). And it's a long-term committment--they live to at least 20 years, often older when well cared for.
Severums are generally relatively peaceful. . . . Once again, depends on your tank size.
the size of the tank is important. especially for Cichlids. many of which get quite large and even a 130 will limit what you can place in the tank.
some largish peaceful cichlids will hit close to the 14"mark and all cichlids to some point are territorial.
some are peaceful to the tank mates but may have issues with others of the same species..or if you are a few you wind up with a pair.
I like Geos and sev's I consider festivum a great cichlid but not on the largish size.
if over 55g a severum would be nice, but having neons with it might prove to be a little too tempting. they are generally non-aggressive, but pretty much all larger cichlids tend to be opportunistic eaters. if you like the looks of a severum though, there are plenty of other tetras that aren't quite so snack-sized.
silver dollars could be another idea they get as big as the angelfish but they may eat plants unless given lots of vegetation also they are schooling fish
+1 for silver dollars. You can forget about keeping live plants with them though, they'll eat them all. Some species can grow to 8" but the most common types found in the stores grow to about 5-6".