1962 Valiant Gas Tank
Just to toss in a little mix in this discussion... In my 63 Valiant I cut out the trunks spare tire wheel well (I was running a tire size that would not even fit in there anyways) and installed a Ford Falcon gas tank... thus it became my trunk floor... (and saved weight)
I know this is not for every one... But I did race my 340 powered 63 Valiant and this fixed several issues for me...