[scooder]

Your gonna need a different ignition with dual carbs.
A converted sbc delco is your best bet.
They are available from a few folk on here. Charlie Ny is great guy and will set you up with the ignition with mechanical AND vacuum advance, this is the best way. Bubba does them too but prefers to do mechanical only.
Don't buy a store bought ignition! These mostly have completely the wrong ignition curve.
Martin.