[Happi1fla]

Greg, sounds like you have done some research, not sure if this helps,
. Found a builder through the Maintenance Shop of a small airplane training school they had twenty planes or more that replace aircraft grade aluminum tanks from time to time, my friend was a mechanic their and helped ,he’s moved back home to California but may have an idea, If you can’t find an outlet , Also not sure of your proximity to the floor/deck ( with tank installed) but you may have to keep the fill tube like the original in height so it doesn’t raise into the floor/deck. This happened to me. The builders cut a square out of the old tanks fill tubes and welded back into the new one. Good Luck with this.

John