It could have blown the head gasket or done a few other things. Most flat deck and heads and good gaskets will with stand being overheated with no issues. If its a stock tight clearance engine, heating may cause gaulling everywhere, pistons, cylinder and such depending on the temp it reached. It could also crack steel heads pretty easily with no cooling system and leaving it overheating. Its really hard to say.
I run alot of blown street engines, so to me a overheated 240 degree engine is not any sweat.
Goodluck!