Ooh, that looks pretty bad, sorry. I have a few ideas, though I only think one is a good one. Here they are, in the order that they come to my mind...
-Get donor shell and swap front ends with firewall, add bracing
-Remove all of the patch stuff and see what's left, then start from the top of this list again
What are you goals for this vehicle?
Welcome to NICO Club and best of luck with that car. You can search the forums for rust and restoration projects to see some people's handy work with metal. It's very labor intensive (i.e. expensive).