carb size for 340 4-speed

Hi this is Bill I,am running a 340 hiperformance in my 73 scamp.I had one of the carbs on mine when i got it.It would not stop leaking .I put on an edelbrock 650 cfm that is what they told me.It is a good carb needed a little adjusting but give good mileage and has the get up and go when you want it good luck