Not being able to see what kind of corrosion you are talking about makes this just an opinion. If I had a fuselage with light surface rust I would leave it as is till after I flew the plane and made sure it was what I wanted. Model 1's are not real desireable planes so there value is fairly low, under $10K flying. Me I like them and operate mine as a heavy ultralight. How about some pictures? What S/N? Mike