Weir slot size for overflow baffle?

[Fizbang]

So Im going to DIY a new baffle for the 75G tank Im working on. The original baffle only covers 2 of the drain holes and I want to take advantage of all 4. My question is with a larger baffle how do I know what size to make the slots for proper flow?

 

[lapin]

If the overflow is 2x as long and the other 2 pipes are the same size then 2x as many teeth should work just fine.
I would make the gap 1/2 as wide as the teeth. I would not want to break a tooth.