I will get a photo of the modified AE86 neck using AE71 hose for future reference. Also the AE86 neck does not use a return for overflow, it uses a baffle in the neck, you can see an oval pipe in the tank inlet.
I just used a hacksaw with a stanley blade to cut the neck, held in a vice and it worked fine.
My next step is to sort our wiring. I would really like to try and source original Toyota plugs but need to call them up and see if they are sold separately