Hmmmm.... that is indeed a very strange and unlogic design, and it changes things a bit....
I was thrown off by the statement "glow style carb" so I assumed the spray bar was in the centre of the drum.
I would say, that the vacuum under the valve then has to be supplied to the pressure regulator, in order to keep fuel pressure equal to vacuum. Maybe it needs an equalizing chamber in the line to prevent pulsing.
For example Ducati does this on their older SuperSport models: there they fit two plastic chambers connected with hoses to the carbs, that seem not to do anything, but if you take them out, or if a hose starts leaking, carburation will be impossible to set-up.
These chambers somehow control the pressure in the float bowls and match it to the intake manifold pressure.
Once fuel pressure and intake manifold pressure are matched, bernouilli should take over once more again....