Pbass would have to be at least 2/3rds the size of the tat to not get eaten. It's important to note that in the wild, pbass are a prey item to the payara and you may run into an aggression problem. They have been proven to work in the past though, so it should be doable.
I would imagine a pike characin of the Ctenoluciidae would be able to live in your tank, assuming its big enough to not be seen as a prey item. Unlike the needlenose false gar, they get fairly girthy and wouldn't be as tempting of a prey item. These fish are known as pike characins (spotted, striped, silver), rocket gars, hujeta gars, etc; and are members of Ctenolucius and Boulengerella. They are large, toothy fish that cohab well with other large characins.
I plan to add a pair of Ctenolucius hujeta if ever I can find some large ones!