Narrow "Stock Location" Mount Fuel Tank for 1968 Dodge Dart?

Did some searching but I am not coming up with anything. Does anyone know of a company or place to purchase a narrow stock location/stock mounting fuel tank for a 1968 Dodge Dart?

I'm just finishing up a spring relocation and will be getting it mini tubed next and I'm seeing that I really won't have room to run 3 inch exhaust pipes out the back like I want to. I'd prefer not to have to put a fuel cell in the trunk so I thought maybe someone makes a narrower tank to mount in the stock location?

Thanks in advance!