71cutlass350

So I know this has been discussed before and I've attempted to read all the threads but I still have some questions. The car is in the middle of a frame off resto and I had a shop install all new fuel lines and I'm preparing to install the fuel tank now. The 2 fuel line sets that I ordered was a 3/8" main and a 4pc vapor return line set. I didn't think of it at the time but I think I'd like to do a fuel return on this car to but I never bought the 1/4" fuel return line. So right now the car has 2 lines coming from front to back, 1 being the main line and the other is what I'm assuming to be the hard line from the vapor return that runs to the vapor canister in the engine bay. My question is since I already have this line installed and I wont be using a vapor canister can I use the fuel vapor return line as a fuel return by connecting one end to the correct fuel pump and the other to a 2 line sending unit. Only thing I'm not sure of is the size of the vapor return line, if its 3/16" or 1/4".

71cutlass350

The vapor return line looks to be 5/16" and I believe the stock fuel return is 1/4" so if i buy a couple 1/4 to 5/16 adapters I think I can use the vapor return as the fuel return. Any reason I wouldn't be able to make this work? Thanks