Protecting fuel filler neck from rust

[scherp69]

I've added a 69 Camaro fuel cap to my 68 Acadian (Nova). With that, I needed to connect the filler tube to the gas tank. I made a filler tube to connect the two using 2" exhaust tube. I'm going to weld the filler tube to the floor and paint the outside of the tube to match the area around it. What can I use thought to protect the inside of the filler tube from rusting though? My car is still in the build stage and when I get to start it, I don't want to have to worry about rust in my fuel. I've added a couple pics to show what I'm doing. Thanks in advance.

https://static1.pt-content.com/images/pt/2012/03/P1010482-1.jpg

https://static1.pt-content.com/images/pt/2012/03/P1010484-1.jpg

[shep]

Might try POR 15 it should hold up to the fuel and will not rust.

[Olav]

Tank sealer as used in motorcykle tanks ?

[jpdeuce]

I would brush in the Eastwood tank sealer.