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You are going to need a competent body shop that knows about frames. Make lots of phone calls to them concerning the Corvette frames. No clue if its repairable. I did see for a while that you can buy new frame rails from Chevy but I don't know if they are still available or not and do replace one, means a total disassembly of the entire car or bascially taking it apart in reverse of how its assembled at the factory.
You could possibly straighten the frame enough to get the front end suspension aligned and make the body panels "fit", but it would be a lot easier to cut off the damaged section of frame rail and replace it with a section from a donor car.
OP added a whole bunch of photos ... there was only the 1st photo initially, which made it look like just a battery acid lead damage. Extra photos that now tell the whole story kind of changes the whole aspect of the question.
As stated before, your going to need to talk to a bodyshop who has repaired a hydroformed perimeter frame such as this. They may be able to section at some point close behind that damage, but they may have to go back further than that for it to be an "approved" repair. I would not pay any money to try to repair that however, what really needs to be done is setup/pull and replace the section.
I'm not real good at estimating the value of a wrecked C5, but here are some ideas. Start by estimating what the repairs will cost and subtract that from what you think a salvage title C5 is worth - that will equal what you should pay for it up front.
The problem with buying a wrecked Corvette to rebuild is that so many people want to buy them to strip and build kit cars, so their salvage value remains quite high. A complete C5 drivetrain can probably bring $3k and the suspension & brakes another $1k or so...Part out the interior and any good body panels....