How to block off fuel return line in Classic Industries Fuel Sending Unit.

I liked the video and plan to check out more of his videos today! However my understanding is that the 5/16 tube that I have plugged in the picture is the fuel return line which I would need if I had an electric fuel pump and EFI. The Vent line is run to the vent fitting which is on top of the tank which would allow for vapor expansion. My reference is the 1973 Dodge Chassis service manual 14-54 through 14-59. I wanted to clarify that the vent return fitting is on top of the tank and the 5/16 tube protruding out of the have of the sending unit is for fuel return. Feedback??

I’ve been married for 30 years, I’m used to being wrong!