OK got the gas tank neck stretched.

Pulled the sending unit.
Drilled a 1/8 hole in the top corner, and drained out the last drop.
Set the tank in the hot sun for several hours.
Hooked up the shop vac to blow into the tank.
Welded it up.. and learned something. The neck is soldered in, not welded.
I melted out the solder, so I welded it in. Figured out why the factory doesn't do it that way.. the metal is real thin from the forming process. Stretched WAY thin. It was really tough to find the right heat to not burn through. ( acetylene ) But I got the job done.

Now the tank is mounted, tail lights are in and wired.

Time to get on with other things.