Get one of the Camaro tanks new from Rock for $100 and relocate the fill tube, then buy a new gauge that will work with a GM sender, then get a sender that reads empty at empty. Add a vent so you can actually try and fill it with the angle under the frame.
I might be able to set you up with one I just replaced already set up for a CCX. You won't find anyone will ship a tank that has had gas in it. By the time you pressure wash the gas fumes out and pack it up for shipping you have more into it than the new one at Rock.
camaro+tank+stainless - JEGS High Performance
Find a good local sheet metal shop to build you one.
It's all about options....................