(CUSTOM) 120 gallon tank stock/ideas

hello mfk
tomorrow im thinking about buying a plywood aquarium that is 48x32x18" which measures to 120 gallons.
What kind of fish would you put in there? I have 2 greentexas cichlids so i would prefer if they could co exist, but if not its not a problem. any suggestions welcomes, although i am leaning towards a predator tank.
Also, anything to look out for when buying a used plywood tank + canister filters?

Those look alright, What about a larger catfish?

If i were to get another catfish, Would they work together? if so what do you recommend?

keep the suggestions coming !

What about a planted tank with a black ghost knife??