I tried using those screw in plastic sight "glass" float bowl plugs, and my float level was significantly too high when just below the middle of the "window". The ones I tried are only designed to be used to set the float level and then must be swapped out with the brass plugs. I ended up setting them so the fuel was just visible at the very bottom of the viewable plug, and that car liked that better.

That is where I understand the float level should be. I also run my outboard carb's fuel level a touch higher than my center carb's fuel level, but the outboard carb's float level is still well below the half way point. Maybe I am setting them wrong?

Do you have an actual glass float bowl plug?