I had a similar problem although it did not look quite as bad as yours on the surface anyway. The one thing I would say is drop the fuel tank and have a look on the inside wall of that part of the chassis. mine turned out to be very rusty as the brake fluid had obviously dripped down the side of the tank and taken the epoxy off. I used Hammerite, but everyone raves about POR15, I don't know if it is availible in the UK, (if it is could somone let me know where from.) Thanks James RG England