Had a question about plumbing my new tank. It has a thick overflow but no return attached. There are holes on top of the tank that I believe is where it was previously plumbed for return lines. What do you think is the best way to plumb the return line? Drill the overflow? Pics attached, you can see one hole on the corner of the tank, couldnt get the whole shot in but theres another hole on the other corner. Then 2 holes near the front end which I dont think ill be using for anything. I have never done plumbing this complicated so any advice will be appreciated.