Just got home after picking mum and her Subaru up (1990 Subaru Legacy Wagon) . The radiator developed a leak and she seems to have cooked it pretty badly.
One of the spark plugs had popped out of its spot so I'm guessing at least a cracked head? It was also making a bit of a knocking noise

What are the best options?
I imagine a rebuild wouldn't be worthwhile seeing as the heads are probably knackered after getting so hot. It has just done 300,000 and was starting to use oil anyway
I had a quick squiz on the net, will an EJ20 out of a '98 Forester bolt straight in?
Other wise I'll try and get a second hand or remanufactured EJ22 long engine?
Thanks