In my first picture, the 2 silver pipes are the fuel.
The lower being the feed from the tank
Upper is the return.
I don't have fuel injection, but still has a return.
I can't remember where it is connected.
I ain't going outside to look.....Even Muffin ain't been out today...
I used all the lines from the donor Sierra as they in excellent condition.
So didn't see any point in replacing them.
I wouldn't think there would be any problem with the IVA if you are not using the pipe.
If he askes, tell the truth. You may want to put fuel injection in at a later date.
So though it better to fit the pipe whilst you were building, rather that trying to fit it later.