What South/Central Americans for 55?

In the near future I will be setting up a new 55 gal. with the idea of
having South or Central American cichlids. The local water is quite hard,
which my Malawis and Brichardi love. What I was hoping for is a "Cichlid
Recipe" for some New World cichlids.

Locally, convicts, jack dempsey, green texas cichlids, firemouth and
sometimes blue rams are often available. Would a combination of these work
out well?

Thanks,
Mark