All things are possible when it comes to cars, especially with a new gas tank I went through something similar on my 1969 Dart GTS, I had the leaf springs moved into the rear subframes (before I knew it was a GTS and not a GT like the badges said ) and had to dent in the passenger side of the stock gas tank to clear the right side leaf spring. I was racing it then with no exhaust system, I sold the car and later bought it back. I have started to putting it back to semi stock, I bought a 3 inch dual exhaust kit from Summit, we ended up mounting the mufflers between the outside of the rear subframes and the 1/4 panels behind the rear end instead of putting them in the stock location That ends up making a lot less exhaust noise in the car with those type mufflers You might want to deepen the tank while your at it to increase the capcity