TOPIC: 1968 Chevron fuel tank

Looking to replace the under seat tank on my Chevron but can't find one that fits. Short of going custom tank does anyone know of a permenant tank that'll fit under the port lounge seat or in the pocket beside the port seat?

Moeller makes a port side tank that would almost fit. But it's 8.25" wide at the top and that would put it up against the seat. A side tank 6" wide would be good.

I already replaced the floor so I don't want to rip it back up to install a tank under the floor.

Here are some pics of the location.