Welcome to FABO!
It shouldn't be too hard to find a rust free roof locally, maybe try your local pick and pull.
I actually have one, but you are much too far away to make it affordable for you to ship even if i gave it to you for free........
Try messaging crackedback on here, he seems to have a lot of rust free parts or knows where to find them and is reasonable with prices, he has a good reputation on here and lives in southern California.
Good to see you saved another one from certain death, it looks pretty good to me.