I had a 69 or 70 350 GTO when I was in high school in MN. It had the white tank. I had a problem with it as a gear came through the side of the gear case when I kick-started it. My buddy had the same thing happen to him with his GTO. I don't know if this was common or not, but have always wondered about it.
Anyway, I'd be interested if someone has a 350 GTO for sale (with the white tank of course). I'm not looking for a project bike, just going down memory lane and still riding bikes.