A rising rate fuel pressure regulator and electric fuel pump capable of over 10psi is what you need. You need to understand that a pressure difference between the fuel pressure and air pressure must be maintaned to achieve good mixtures. Take for example a N/A carby setup fuel pressure is about 3psi greater than manifold pressure ever is. So when boosting you need to increase fuel pressure accordingly to boost. 7psi boost should have about 10psi fuel pressure etc etc. i have not had any problems with the carby not holding pressure or draining the fuel bowl (i drilled the needle orrifice out to about 2.5mm and adjust the float level after of course)

As far as the hole on the 32/36 weber that is a fuel bowl vent or something and i found it best to block it off. i am running the same tubro and same carb as you and have had no problems with lean mixtures (if anything i over did the jets and it runs quite rich on secondary.)

I am running a holley blue electric pump with a malpassi r/r reg for a carb. I also modified the tank to have a 5/16" pickup and put a filter (plastic ryco one) before the pump and a Z200 after the pump.