Given what the rest looks like I'd de-grease, wire brush the loose rust, use a converter or sealer on it of the por15 ilk, put some of their hole patch compatable putty in the minor holes, coat it, reinstall new drain plugs, and use it as is. Save the bigger money and time on that trashed mechanical system and get it driving/enjoyed.I stripped the interior out to keep it from being ruined by the rain, since there is no windows in the car. View attachment 172718
Found some rust and holes in the floors unfortunately
View attachment 172719
More pics I see the more it looks like a flood car.