If you can find an 8mm banjo fitting you could easily eliminate that second fuel valve... I've had problems with those in the past where they she'd off tiny rubber chunks that can wreak havoc inside your carb by blocking off the main jet or holding the needle and seat valve open. On my first build I was always getting a sputtering problem and kept finding this junk in the float bowl so I finally just gutted out that fuel valve and problem solved, but it would be better to replace the whole thing with a banjo fitting.
The speed carbs sold by California motor bikes come without this second fuel valve which also makes it a non issue.