Gary,
My tank is installed but, I can make a paper cutout of the side view and radii . The front ,top, back, and bottom are one piece and probably welded at mid level back,( maybe a short 6"weld.) .
the top and bottom are not the same dimension but can easily measure and approx tank level assembly( I would suggest you use a common size sensor flange) the drain plug, tabs for mounting will be up to you.
Dakazman