I blew the head gasket on a 1975 Peugeot 504 Station Wagon back in the early 80's (paid a grand for it). Found out due to the lower hose blowing from the pressure but still managed to limp it home about 25 miles using tape - had to keep stopping and adding tape and water. I later pulled the head and it sat for about a year - long enough for the cylinders to fill with rust. I ended up selling the car for the same $500 (for the parts) - the buyer took fine sandpaper and removed the rust and used a bit of Marvel Mystery Oil to flush the block - put the heads back on it (with a gasket set) and it cranked right back up - it was still running with little or no loss of compression years later. Of course, that engine was more like a tractor motor than what we have, but the point is, your experiences may vary.
-- John