A big job looms!!!
You look like you have a great garage/workshop though so should be ok!
Staring with a new chassis seems to be the right route with that level of rust.
But... jesus there will be some time involved!
If I was 3 months younger....
I'd love the challenge!
Good luck and get a swear-box!
it will need to be large so you can have a great celebration when the resto is complete - if any resto ever is!
It's a bit like an artist with a painting - the secret is knowing when to stop.
I bet the end result will be top notch.