Well, unlike Clone, I've always been of the opinion that anything can be fixed. It may not make economical sense to fix it, but it doesn't mean you can't. Hell, my if I had a nickel for everytime someone told me to scrap my Regal because it was too rusty, I'd probably have enough money to buy a
Grand National.
However I still agree with Clone that rusted frames can be a safety issue, especially when your dealing with a lot of horsepower. I were you, I'd get a 3 lb mini sledge, beat the hell outta the frame and find out what is good and what isn't. Best case scenario, take it to a frame shop, they weld it up and plate it. Worst case scenario, you have to replace the frame. Rolling G Body chassis's are a dime a dozen. Don't let anyone tell you to 'part it out' or 'find a different project' over some rust. If everyone did that, people would be scrapping these cars left and right.