actually if the motor has 2 carbs it is not recommended to run dry, as the top carb runs out of fuel/oil first, thus those cylinders do not get lube. should be fine with seafoam.
I leave the carbs full and just unhook the line.I also use the spray version of Seafoam (Deep Creep) to fog the engine till it stalls it out.It has been sitting a few weeks now with black goo dripping out around the prop.I figure thats just the Seafoam and fuel mixture.In the spring i bet it smokes like a freight train until the crud gets burned out...