Since someone asked about the fuel line setup. They originally had a “T” splitting them off of 1 petcock outlet. I put a 2nd nipple on the petcock, and ran 2 lines down to each carb.
The scale on the right is metric. So it’s at 2.3cm (23mm)
I hooked a fuel line up to a carb without the float bowl on, and lifted on the float arm. It stopped the fuel flow.