Having recently been through a major rebuild, including fitting a fuel cell, I would recommend having an in-tank pump option. Trying to fit a large capacity pump, below the standard fuel tank outlet, after an in-line filter (for pump protection) and routing the larger fuel lines to clear the front suspension cross member was a major problem.
After many attempts at trying to fit the larger capacity fuel supply system I gave up, sold my brand new 044 pumps, removed the standard tank and purchased an Aeromotive fuel cell with an in-tank high capacity pump (A1000). This simplified the install and solved many of the routing / mounting issues. However the rectangular shape of the Aeromotive fuel cell is far from ideal in a 911. The shape of your proposed tank would be awesome.
Additionally, making the height of the tank to suit the standard 911 fuel level sender would also be a nice feature. I ended up having to shorten the 911 sender by ~15mm to get it to fit - a lot of work and a major pain. Using the OEM level sender simplifies the install and for many "street" driven cars is a needed feature.
I hope this helps your product development.
Richard.