Per your post when you cut a rectangular hole in the left sponsoon did you have to have the interior baffle welded or was it already completely seal welded. I too want to locate my fuel pumps in these locations on both sides.
I remember seeing your gtd for sale years ago and that you were planning a move to Mexico. I now plan on moving there in the next year or so. My wife is from Mexico and I have thought about San Miguel de Allende, Queretaro and the Lake Chapala area.
Do you plan on going back to Mexico someday?
I too have a GT40 (CAV) and a FFR GTM. I will be selling my toys sometime this year.