You can do both of those things, won't matter. Usually feeding the manual pump with the electric will resolve the vapor lock issues.
Here's one other thing you might look at, and I have personal experience with this one. I would shut my 69 Mach 1 off hot, then five minutes later start it. It would die about a quarter mile down the road, and it was not from fuel starvation, it was from flooding. What I finally figured out was happening was as the car heat soaked after shutoff, the carb and fuel lines got pretty hot. I would start the car, and then the overheated fuel coming out of the fuel line would hit atmospheric pressure when it entered the carb, and it would boil. Modern gasoline has a very low boiling point, around 150 degrees or so. Anyway, when the fuel started boiling in the carb it would spit out of the carb vents and go down the throat of the carb, and flood the engine. Felt just like running out of fuel, but it was too much fuel instead. I finally figured this out one hot day by letting the car run in the driveway with the hood down and the air cleaner off, then shutting it off, and restarting after a couple minutes. When it started to die I lifted the hood and observed all this fuel flooding out of the carb vents and into the carb.
I solved the problem by installing a return style fuel system, so that hot fuel couldn't sit in the lines in the engine compartment. I kept the mechanical pump. I also insulated the lines to keep them from getting too hot.
Any easy way to check for this problem is to put some 110 octane race fuel in the car. It will have a higher boiling point, and keep this from happening.
