When I bought mine in march my return line off the fuel filter was plugged. I, with the honest intention of fixing all the PO screw ups, was gonna fix that and put back in my return line. So I did. My car wouldn't start. Long story short, I had to plug that line back to make it run. I replaced my fuel pump because I wasn't getting fuel to the carb, I replaced my rubber fuel lines on both sides of the vehicle and I replaced my fuel filter. None of those helped until I plugged the return line back.
A) if you are gonna keep that return line make sure that line is on top of the line going to the carb or you cause vapor lock
B) if you are like me and your 600cfm Edelbrock is too thirsty, you might consider plugging up that return line