IN, means fuel supply from the tank!, out means to the carb!, and there should be a return port to go BACK to the tank to send the excess!

 

if i'm reading that right, parts guy is wrong...the dual inlets on the holleys you referenced are fuel going IN the carburetor, one for the primaries and the other for the secondaries, the carb has no return line as has been stated by others...so, seeing as you only have one inlet it sounds like it's the ford style holley in which case fuel should be going into the primary float bowl and running into the secondary float bowl via a metal rod between the two...in either case you don't have a return line coming off of your carb, the return line will come off the regulator you have

 

well if im not mistaken, if your still using the stock fuel pump you are going to need either a good aeromotive or that mallory regulator like i used. You have to have one that will hold up to the 55-60psi and cut it back to 6 or 7. It can be done using the stock intank fuel pump. I had to cut and splice a wire on my fuel pump relay. Its located on the left side under the hood. Had to do this so that the fuel pump would always run when the key was on. if u need help i know that old truck of chris is done the same way. Boonie has it now so, all you would have to do is look at it. Let me know if u need any help.