E-A-G-L-E-S
Could you post a picture of the your overflow setup, maybe once we can see it, we could offer more detailed guidance.
How far does the water drop after going over the overflow? If it is level and there is no drop, I suspect your bulkheads are the cause of high water.
1" drain bulkheads seem small to me, even two of them, while they may work as water will have to 'build head' to get the volume thru them. If they are mounted too high, this would cause the water level to back up over the weir, sort of like a tailwater effect.
If there is a drop, then the length of overflow is too short and notching/widening notches will help.
There is an article/thread around Anthony's old forum that discusses the benifits of lower flows over the weir and thru the sump. Throttling back the flow 200gph or so will make the biggest difference here and you may not have to modify anything.
...and with having a wave box installed, the return will not be a significant source of circulation anyway so it wont be much loss in that respect either; if you feel it is, use a Maxi-jet to make up the 200gph difference.
Chris