Fairly common to pop head gaskets on falcons of that era
pull the head check for corrosion cracks and hardness
machine flat and refit a straight forward easy job.
if it starts and runs after the overheat it is usually OK in the oiston and ring departmet
make sure you fit new head bolts
done a few that have had head work and reused old bolts, a couple of weeks later the bolt heads pop off , not worth the risk.
and yes they do stink when the overheat
check radiator if system pressurized the tubes swell, and steam will kill plastic tanks.
one thing , if it was a japp diesel it would be dead.
they dint like getting hot.