That is Snorklefork's bike, and he has every intention to move that gas tank around. In fact I believe he is ditching it entirely.
Here is a bike I used to have. Not a CB350; its a Suzuki T350. It has a CX500 tank with the emblems holes and gas cap lid filled:
You can click the picture to go to an old website with a ton of pictures from when I was trying to sell it.
the cx tanks are too wide for cb350's. looks great from a side profile when you've taken the time to level it out but it hangs way out over the engine. and in the case of this bike the seat used buy the previous owner fits the tank but not the bike as well.