'66 Barracuda gas filler/tank

I discovered my '66 Barracuda project car doesn't have a gas tank. I now have one (+ strap & sending unit) on order. In the mean time, I'm trying to figure out how to remove the filler neck to replace the broken piece of hose that connects the neck with the vent tube & I can't figure out how to remove the filler neck to make the repair. I'm also trying to figure out what piece(s) I'll need to attach the filler tube to the gas tank. I have a couple of manuals, but none show an early Barracuda. Can anyone provide a diagram? What parts will I be needing? Thanks!
There's a rubber grommet that fits in the hole in the gas tank the filler tube fits through, and seals the opening.
On a Dart, there's a metal plate bonded with a rubber covering where the tube goes through the floor that seals it. They are available from DMT:
Mopar A Body 63-66 Barracuda Dart Fuel Filler Tube to Trunk Floor Seal