I've owned a couple of Cavalier GSis and they are up there with my top favourites out of my 55 car history. Brilliant cars - just a shame about the rot.
Yeah mine was rusty, it had a lot of welding done before I bought it but the arches were in a mess and I ended up sorting them out to look ok with fibreglass and filler but I rattle canned them when it was cold with my Mrs constantly disturbing me and they looked shit.
The bodywork certainly let it down.
I ended up selling it to an Irish lad who came over on the ferry from cork and he loved it, only really wanted it for the engine but apparently his dad was so impressed with how solid the car was he put his 2.0 8v out of the Astra in it and it survived out there for many more years which was nice to see. Apparently anything beyond a pile of rust was rare out there, I'm guessing due to a Westerly and very wet location and lack of required MOT for a number of years let shit get neglected?