Drew, if you found rusty fuel lines, and have a funny guage, I'd recommend you pull the cover over your fuel tank under the carpet in the back (you know where it is) and examine the sending unit and fuel pump harnesses, next time you get a chance. I went to start Betsy II (it was parked in the garage) one morning, and it wasn't getting fuel. I traced it back to the pump, and lo and behold, when I checked the wiring harness to the top of the tank, the wire had corroded to a green dust, which blew away when I pulled back the insulation! A newly spliced wire fixed it quickly.

Just something to check, if you're dealing with rust and finding funny symptoms with the fuel guage.