I have to agree, drilling now will be the best thing you could do, well next to setting a sump up.
I will never go back to a hang on overflow, never had any floods but it could have easily happened. The 40b is ideal for that tank too as a sump, I use one on my 180g tank. Plenty of room for a decent skimmer and anything else you may wanna toss in there, depending on your needs at the time.
I know it sounds like alot of stuff, the sump and drilling, but trust me and the others, we have learned from our mistakes and only want to have you avoid our pitfalls. lol
I even drilled my 40b tank and stuck a 10g sump underneath. lol So easy and so much better to maintain the tank. You will thank us, thats a guarantee. lol