Custom overflow box questions

I am ordering a custom overflow box from Glass-holes and want to make sure my dimensions are ok? I have yet to see this setup used with the bean animal and very unsure about my dimensions working properly.

Overflow is Bean Animal with 1 inch plumbing.

I am planning on the dimensions of the overflow box to be:

Length- 11 1/2"
Height- 5"
Depth- 3"

My downturned elbows for the bean animal are 10" apart. Is 3/4" gap enough on each side?

The depth of the downturned elbows for the stand pipes are 2" . Is 1" enough of a gap?

Should my overflow box come up and touch the rim of the tank if the box has teeth?

I'm sure these are stupid questions but not sure if a bigger overflow box is necessary for proper skimming and aeration....

Thanks all!