The return lines of the '70s, were all from that emitions crap. They asumed that it would increase mileage by returning the unused fuel to the tank. While it is completely ok, and won't cause any improvements, or adverse conditions, the return line is basically a person to person preference. There is absolutely no reason NOT to use it, but also no need TO use it. I can see the use of it in Jacks case, there are ports already there, and the donor most likely used it, why not just use it still, but again, it boils down to mere preference. Either way, is completely ok. If you run a high volume/high pressure fuel pump, and will use a regulator, you would absolutely want the return line available, as it can increase the life of the spring, and diaphram in the pump, at least that is what many people claim, but I have no personal experience with that claim.

 

Thanks for all the input guys. I have finished installing my fuel line...... I installed a rollover vent tube on one port and the main line comes from the tank to an inline filter, to a Pro Comp electronics fuel pump preset at 7 lbs then into an adjustable regulator that I can range from 4-9 lbs then into a second inline filter at the carb. Now as long as I can get the motor to start we'll be golden....still working out some timing issues.