Wouldn't running the bowls dry cause deto? If he's not running a pump or oversize bowls I dont think it would take a very long pass to run the bowls dry.
Also, I dont think you can use standard size mains jets. I think they have to be drilled out to size. I know my mains and tubes were drilled but I'm not sure about the smaller carbs. If your running standard size main jets maybe that lean main jet could be causing deto.? I'm by no means a expert on alky, I'm learning about it myself. Someone can chime in if I'm wrong.