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

they make oval exhaust pipe, that is equal in overall surface (or however it is measured) to 3 inch round tube
(think of it this way, a 2X2 square is the same surface as a 1X4 sqaure, the same principle applies to round and oval, just with more complex calculations)

well, someone done did these calculations and made some oval tubes that will flow the same as the round 3 inch tubes but are narrower to fit in between relocated springs and stock tanks