Cutting internal overflow for turtle tank--Anyone done this?

Hello,

I am setting up a 75 gallon tank for my RES. It's an Oceanic reef ready tank that I found on Craigslist. I also purchased a 120 gallon wet/dry filter that I was planning on using for filtration. The problem I am having is the internal overflow is obviously made to have the water level to the top of the aquarium, and I am needing the water level to be significantly lower. I thought about taking the existing box out and making a new one, but from what I have read they are almost impossible to completely take out. I also thought about just drilling 2" holes all the way around the existing overflow at my desired water level and covering them with some sort of netting.

Has anyone ever cut down an existing overflow? Should I take this to an aquarium shop and see what they say? I really want to get my turtle into his new aquarium and this is the last obstacle I am facing. Any suggestions or ideas would be greatly appreciated!

I am attaching some pictures of the aquarium I have. These are just pictures I found online, but it's the same tank.

 

The holes seem like a great idea but remember you will need to lower the dorso pipes inside as well, as long as you have them lowered I think it should work just fine. I never did this so deff. check with someone else before doing anything. Or you could get a zip saw and lower it or take it out completely and just leave the pipes there at your desired height.

 

I have already taken out the dorso pipe and will definitely be cutting it. I thought about taking a roto-zip to it and just cutting it down, but I can't think of a way to secure a guide on it since it's curved and I don't want to just eye it and have it come out looking crooked and ugly.

Do you think the holes would allow water to pass thru fast enough? I haven't purchased a pump yet but I was thinking about getting a 1000 gph pump.

 

tape one of those semi flexible rulers side by side with a small gap in between for a guide