Greg when you say the front carb was "higher" do you mean the float is higher when the carb is inverted? That would mean the fuel level is in fact lower.
What you call the hot start valve is actually a two position fuel bowl vent. It is for air flow, and "fume" flow only. At idle it vents to the charcoal cannister, and at any appreciable throttle opening it vents to air cleaner face of the carb. If the fuel bowl is flooding, fuel will come out of the hose, or out of the vent hole on the carb face.
Do you have a fuel filter - and is it in the hose from the pump to the carbs? If yes, is it above the exhaust manifold number one runner? Remove the filter anyways, and put it in the hose leading to the pump. Don't use one in the hose between the pump and carbs. A filter is simply a resevoir of extra fuel looking to boil. SU's aren't that sensitive to unfiltered fuel, unless the tank is rusty.
You may still have a leaky needle valve. Did you determine what kind you have?
Don't give up yet.
Rhys