FWIW bad plugs are usually a symptom of another problem. Occasionally you may have plugs fail but they are usually the last thing to go. The world is full of "mechanics" who "solve" problems by changing the plugs. They are not solving the problem they are temporarily delaying it's reappearance.
The symptoms you described could be poor ignition (especially if you contact points) and possibly bad fuel worn rings or any number of other things that can foul the plugs. I've been running B18s long enough to know that ignition is the #1 problem. Fuel supply is a close secound with that long thin fuel line leading from an old fuel tank through a marginal fuel pump. BTW if you run out of fuel again, start the engine using small amount of fuel dribbled into the carb throat as the fuel pump has trouble creating enough vacuum( remember you used all the fuel so there is only air) to pull fuel from the tank at cranking speed.