Holley float level

I bought a new Holley "Brawler" with the sight glass and it says to set it half way up. There is a casting line on my bowls.

I also have ready AndyF say the same thing and seen photos from him (IIRC) with lines drawn to show how the old sight hole was set higher on the bowl so the middle of the new one is the same as the bottom of the older ones.