IOS Tank Parts DIY questions

Hi guys I'm trying to DIY an IOS tank & I was wondering if anyone can point me in the right direction...

You know some IOS tanks have a plate (For a lack of words this is the best way I can describe it) at the corner & they have teeth at the top to allow the overflow to flow into...

Any idea where I can buy one for a 2ft X 1ft (Height) tank?

I will be drilling the hole myself & putting the attachment on my own plus do the piping...

Any help is appreciated...