I have more than that on my 75g. I have an Emperor 400, AC 500 and 2 301's. That's about what I use for cichlids and piranhas. I took 1 301 out and turned off my AC500 tho because all I have in there right now are 6 red belly piranhas that are about 1/2" and a Melanochromis chipokae so I don't need all the filtration and water flow yet but when the piranha's get a couple inches bigger I will turn it all back on again as the water flow makes them stronger.
I don't think what you have is overkill at all as long as the fish aren't constantly fighting the current.