Stock size is equivalent to AN-5. I just completed making my own fuel lines from 3/8" Al tubing and AN-6 compression fittings, and it was tough. I used the stock lines as a guide, and the 3/8" tubing barely fit back into the stock clip retainers under the car. I'm be running a CJ secondary rail with ID2000s, coming from a custom surge tank out back with AN-6 outlet/inlet.

If you will be using pump gas You don’t need to upgrade all your lines.
Just use -6an from the engine bay to the rails and Fpr. Get a rail with an aftermarket dampener. There is a reason all the OEM’s run a fuel dampener.

Make sure you change out your stock fuel filter that is over the differential. Relocating it is a good idea as well so it’s easier to change on a more regular basis.

I run the same turbo on ID725 primaries and ID2000 secondaries with one Walbro 485 pump and CJ pump hanger as well. when you start making over 500hp+ you can upgrade everything to -8an lines.