If you chipped a nail would you lop your hand off? You seem to have put a good deal into this car. If you like it then fix the rust. Do it properly. Fender lips are the first place to go on these cars so I hear so have them sandblasted and treated now before anything gets out of hand...or sell it really cheaply to someone who will fix it or use the good parts. It all depends on what the car is worth TO YOU.