Tom, Anything is salvageable. I do not weld, but i know a man who is a master welder and welded to spec many times, government contract work. I have had several frame repairs done by him and aluminium fin replacement as well as broken case repair. The frame repair is an involved process but easy. You're best off finding a spare frame to use for parts, but consideration must be given to which part of a frame is going to be used form a later frame, as the later frames have bigger gussets, different welds and other nuances. But, any of this can be overcome. I take it the area of the frame you are talking about are the lower frame tubes, under the engine. Common area to rust out, usually sitting outside, moisture accumulation, freezing & bursting. These frames incorporate thin wall tubing. I have heard of sandcast cases from what i consider reputable sources. Look up Andy Morris at mid-Ohio this weekend, he can be of assistance. There has to be excellent welders in your area. However there are definite considerations and procedures to deal with in frame repair, but they are not complex, any good weldeer should know how to make these repair decisions. Marty Kitner, club member, has experience with frame repair. If you can't find help in your area, i can take care of the repair as well.