Early 67, want to convert to 3/8 2 pc fuel line from tunnel mounted 5/16 line

[Wallgeye]

Currently working through a brake and suspension rebuild. Original brake hoses and funky Cougar only strut rods still on the car!

While removing brake lines i noticed that the fuel line is looking pretty crusty. Original 5/16 through the tunnel. I am wanting to update the fuel line to 3/8 2 piece while I’m in here. I have all of the parts, sender, line, protective plate, clips, etc,. What I do not have is a drivers side torque box with the hole in it for the fuel line to pass through.

I tend to overthink things and have been poking around online seeing this project mentioned but not discussed with much detail. The one video I found shows drilling it out with a 3/4 inch holesaw but no mention of how they chose where to drill.

Is it as simple as running the new line up to the torque box semi installed and marking the box for a location?

[Since1980]

Yes, it is just a hole. Here’s a view of approximatation.

I have never seen a ‘67 or’ '68 run the fuel line any other way except through the torque box, along the unibody frame, take a left untill the pinch weld. following

the rocker untill the front leaf spring mount.. ect.

Is it possible the box was replaced?

It’s possible it is very rusty and was covered with a wall of unknown material.

Preformed lines are available and work great.