If you had a 75g tank all circulated and ready for fish, what would be your stock of choice? This can include plants, gravel/sand, and scenery as well.
I'd put some major amount of scrubbies in with all the other types of biological media and loads of sponges for mechanical filtration and a 8000lph pump and make a sump for my 350g ,oh already did that lol.
Seriously though I could go for some altum angels depending on the dimensions or most likely some small upper jaw polypterus with some nice vallis and sand as substrate.
my 75 when i was happiest with it was delhezi 2 sens palmas polli an angel and a school of buenos aires tetras heavily planted with driftwood and a sand bottom, it was very peaceful. if i had a 75 back today it would be a flowerhorn all the way. may be evil but i love em and miss mine greatly