That is the big question.
Chances are, if you can see visible rot there, then, you have rot in other places you can't see until the body comes off the frame....ie, total frame replacement needed.
Horror stories? I don't know about that. Switching frames is not a "fun" job when you have to do it. It is fun when you are just pulling it apart to clean, paint, detail, then reattach.
In your case I would suggest a complete frame replacement. Remember, the serial number for your car is stamped on the frame rail above the left axle. See your local Department of Motor Vehicles to ensure you follow the correct procedure to re-certify the VIN on the replacement frame. It will project you later down the road if the car is ever stolen.
Once you seperate the body from the frame, they don't want to go back together easy anyway! It is a back breaking procedure to lower the body back down, while you set the frame mounts and shims to get the correct fit. You will have to lift it up and down several times, open and close doors, look at body gaps and fit until you get it perfect. This is easier on newer rubber bushing Sharks, but yours has aluminum spacers between the body and frame. YOu will find they will crumble in your hands when you pull the body off. A new kit is about $80 and well worth it!
If you car is a stick, and as long as you are not a purist, I suggst you find a automatic based frame because they have bolt in cross members. It will make pulling the trans at a later date an easier chore.
Good luck!
