On a '67, can the main fuel line be replaced without raising the body from the frame?

I would say yes, BUT. I did it on my 68, and it was a pain. A new prebent line will not work easily, because it goes between the body and the frame by the control arm mount, and around the upper shock mount somehow. If you make your own, you'll have to splice it a time or two more than the original factory line, but it can be done pretty nice that way. When you cut the old one off, try to save it as a template to bend the replacement. Keep in mind though, I ruined many many feet of perfectly good straight tubing before I got it right!! Good luck!

chris