Grandma's 73 Gold Duster

Misty, Near me is a radiator shop that also works with gas tanks - they clean them out and use a special paint to coat the inside. When they done my tank, they cleaned and coated the inside of the filler tube also.

If you want to DIY, I think you can get that stuff from Eastwood.
This is if you cannot find a new or clean used tube.
And as stated, we want to see pics!
C