I've got it close, much like Jason I have it so it just starts to spill into the emergency line. I would have went higher on the emergency line but I have Albert's kick *** anti syphon pretzel on the return and it takes up a bit of space in the overflow box.
As mentioned PVC gates are impossible to find in Calgary. I'm almost tempted to by a crate of them online and sell them on Canreef
Thanks for the tips guys, I am happy to know it is not just me.