[HO455]

From the photos it looks like you have C-notched the frame. So I'm assuming you are raising the floor and able to move the tank up. That might make re-clocking the fill a workable solution since your whole floor will be a custom installation.

One thing to keep in mind is to try and avoid having a low spot in the fill. That will make putting fuel in slow and tedious.

The factory used that smaller line on the fill as a tank vent to allow faster fill-ups. Your new tank doesn't appear to have any provision to reconnect that vent. The lack of this vent with any low spot will become a constant source of annoyance every time you need fuel. Personally I would find a way to add that vent into the tank.

My 70 Javelin has a poorly designed fuel fill from the factory and forces me to hold the fuel nozzle in the fill and then only let the minimum fuel through the nozzle. It probably worked back in the day but with today's nozzles it's a pain.
Forgive me if you were already aware of this. Good luck! Keep us posted on how it works out. You're not the only one looking to do this.