this tank needs to be plumbed through the bottom in order to hide the wires and plumbing as this will be a show tank. The sump will sit in a cabinet below the 6ft tank hidden from view. The 6ft tank needs to be seen from both sides but not the ends. It will be used to house Tropheus so filtration requirements is very high.
Just looking quickly at the pumps it suggests and you could filter around 600 gph at 0 head. As for plumbing it, it would depend on how big the inlet pipe is. But you'd run a drain line from the tank to the sump inlet then a return line from the pump to the tank. Would need to make sure the drain line and return are close to the top of your tank's water level so it doesn't back syphon too much water if the pump stops. Shouldn't be too difficult to work out. Some flex pvc would make it easier to plumb.