Redo
Yes, I tore it down. All stock is back in the 10gallon holding tank. I could only around 200GPH tank water turnover from my "800" GPH overflow. I coulden't even get it to properly skim, the water surface. I figure I'm very early into this project and if I'm going fix things, now is the time. Sooooo, I got a FijiCube 1200GPH overflow and grabbed a new 40 breeder from petco for 50 bucks.
I bought a 6 dollar plastic tub and installed my new overflow and tested with my return sump. It easily handles full power of my return pump. Also, I know exactly where the water level will be so I know how to properly drill the tank. Why I didn't do this to begin with, IDK.

A funny side story... When I grabbed a new Aqueon 40 breeder from Petco on their sale and when I was getting ready to drill it, I noticed a sticker on the bottom of the tank.
So I google the text in the picture and it takes me to the Aqueon page and it states that sometimes regular glass is subsituted with tempered glass and when this happens they apply this sticker to the bottom of the tank. dang, I'm glad I checked it out. I thought it was just a generic safety message. My son had just bought a 40 and his don't have the sticker so we swapped. Thant could have been a mess lol.