I've come up with a modified version of this. Glass is cut, progress on new tank slow, so not complete yet (we have triplets, 4 mos old, so time is sparse. . .)
I originally drilled two 1-3/4" holes in the high back wall of the tank intending to put an internal overflow across the back wall exiting through two 1" bulkheads (hence the needed 1-3/4" holes)
Two problems: flow limited by 2 gravity-driven 1" returns, and making room for the downturned street elbow on the tank side required the overflow to protrude into the tank too far. I wanted only 1" or so. I had intended to put durso tees on the outside.
Based on ideas from this thread, I decided instead to simply leave the 1-3/4" holes, put a 4" tall x 1" deep weir style overflow along the back wall of the tank. I then will have 2 overflow boxes on the outside of the tank centered on each of the drilled holes, styled similiarly to what you are all using here. Each esternal overflow box will have a pair of 1" retruns using stockman standpipes.
This compromise will greatly increase the flow capacity and reduce the projection of the internal overflow into the tank!