I understand your post a bit better now. Though you make mention of a fuel pressure regulator which is an item I tend to associate with fuel injected engines. Also fuel injection tends to make use of a higher pressure fuel pump which if fitted to a carb fed car could perhaps overcome the needles ability to shut off the fuel at the correct float level, if at all..?
One other thing it seems you may not have mentioned is a fuel filter to inhibit crud from the tank entering the float bowl...?
I have an electric fuel pump and regulator on a carbed engine. It means that you get consistent pressure (set by the regulator) rather than the ebbs and flows you get with a mechanical pump. The regulator can be set to mirror the pressure provided by the mechanical fuel pump so no more likely to overcome the needles.
