Overflow tubes are a no-go for me. I'll rather not have a garage-house fire . . . .Without overflow tubes, the gasoline fills the cylinder then trickles out onto the same floor with the same fire hazard.
I "reconditioned" mine and fuel leaked from the switch so I gave this a try, looks exactly like OEM in every way and I now have peace of mind. Replacing the petcoc on these old bikes is now preventative maintenance. $30
https://www.ebay.com/itm/313781928845