Need some advice for set up

[Tacoyaki]

Hey guys I was wondering if any of you could offer some advice towards this small project im about to start. First of all, I was planning of building a stacker stand that could hold 2 20 gallon long tanks and a sump at the bottom.

That part isn't so complicated but the part I need advice on is the plumbing. After finding out the cost of getting the tank drilled I've been trying to stay away from that idea.

Anyone with plumbing experience know a way where I can get the water to over flow from the highest tank to the second tank then to the sump? Or am I better off with getting the pump to direct water on both the tanks?