drilling and over flow boxes

[Ultimatom]

I changed my mind about the whole thing.. im bringing back the tank i got and will buy a predrilled with corner overflow in it . It's cheaper and i really didnt need the lights ,heater and stuff that was coming in that "kit" i got. I'll chip in 20$ and I'll get that 55g with a 30g tank to build my sump. Would you advice me to drill the sump for the return line and get an external pump or just run a pump in the sump?