Okay, that is a good lead. If that much fuel is going in I suspect the valves are out of adjustment. Maybe too tight. While I can't speak from experience because i've never used custom carbs, (my bike is rock stock) that sounds like an overly tight adjustment of your intake valves, causing an excess of fuel to be sucked in. Your exhaust valves might be loose too, allowing too much out.
My bike popped when my points were even slightly off, and my fuel wasn't getting burned.
If you're willing to fix it, find stock carbs, start from zero.
PS, the weird jetting is that you're getting the advice your offset of main to idle is out of whack. IE, you're set up for old carbs in terms of jets but the new carbs aren't working well with the jetting... again, my bike is stock, so I'm talking out my donut hole here.
I also remember people making a liquid carb syncher out of tubing and some water and food coloring....manometer I think it's called??