I think you'll likely be fine with the return pump and loc line returns. I have a 1400 or so GPH return pump and plan on using a 2' spray bar. I have never had success with powerheads. They tend to blow my leafy plants all around. I think those will both be massively oversized. I would, however, set up the tank without the powerheads and see how the plants sway. Add the power heads and see if it is a toilet flushing or not. Go from there. IMO, too much flow. Others have had success with more flow than I have though. Amazon swords don't appreciate high flow in my experience and I've had them in every tank.