Yes you could but remember the overflow will stick out about 4 inches inside the tank if you go for an internal overflow. If you drill it, go with an external overflow so there will be no overflow box inside the tank. This is an example of what I'm talking about with an external overflow box:
Everything is outside the tank so I can maximize volume and aquascape right up on the glass and not have any shadows from the overflow box.
![overflow-1.jpg](/proxy.php?image=http%3A%2F%2Fi62.photobucket.com%2Falbums%2Fh115%2Fjeffb3t%2Foverflow-1.jpg&hash=681f9aa78d44d4aaf129af6fec24fbde)
Everything is outside the tank so I can maximize volume and aquascape right up on the glass and not have any shadows from the overflow box.