My 70 deuce convertible has severe cancer in the frame rails in a few areas. The areas near the firewall are almost rusted through and the frames about to snap in half. I bought a 69 Electra four-door which the frame is not exactly interchangeable with the 70 convertible, but the sections in the convertible that’s bad is good on the 69. My plan is to replace those sections from the 69, but I have never done anything like that before. Any advice you can give a newbie on a frame repair?