The engine in these had an aluminium cylinder head on a cast iron block, with steel studs . When a head gasket blew ,the head was usually corroded to the studs. The only way I found to remove it was to put a plasticine (silly putty) cup around each of the studs, fill with vinegar and suspend the car on a block and tackle through the spark plug holes. Leave overnight ,usually worked. If not, heat, but careful not to melt the ali head.