90 Fresh---->Salt Drilling Tank?

[Chammy]

I have been searching forums and the internet on this question so I'm hoping someone can help me out. I am converting my 90 to salt and will go with a sump with skimmer as opposed to HOB Remora. From what I gather, it is better to go with a "drilled" tank 3" from top instead of an overflow box.

If my tank has no holes, is it a hassle to drill it or should I just go with an overflow box with a "custom" drilled nozzle hole to prevent backflow if power goes out?

This is basically my biggest dilemma. I don't want to come home to a flooded basement, and I want the better skimming strategy of the two.

Please help me out.