Only issue I see is the P-bass. Eventually gonna need more space. I thought Kels stayed smaller but have seen some massive 18"+ examples and they are too big for any 72x24" tank.
Tank size for a solo hysterix is ok. Don’t think you’ll be able to get away with keeping clean water with the other fish and fx6 for filtration. More water will dilute the waste but even then ull need a drip and k1 filter etc. Rays need really clean and stable water.
I think you're after quite the overstocking already. I would greatly reduce the stock plan. We all want many fish but there are size constraints . Think about what you really want to keep and when you decide on that, think what conditions would those fish really need.