+1 If you're storing it outside and intend to spend money on it, I'd look elsewhere. You should prioritize getting the cleanest body you can, it will make life exponentially easier for you long termYou can see the cracking gutter seam sealer in the second photo that lead to the rust.
If you want to fix it, you’d need a donor roof and you’d cut current one off and weld the donor on. I’m guessing it’s down the A pillars too. Also, when the roof seams have been leaking, usually the floor inside of the rockers is also in tough shape.
If you want a trail rig or winter truck, you could treat the rust, store it indoors and it would easily last another decade.