Am i right in thinking that, apart from the coscast mark under the exhaust port, a coscast head has a little circular hole on the right side of the cylinder head (as you look down on the engine from above) just down from the distributer. A GM head does not have this hole.
If you look down on the engine, its directly above where a water hose exits the block.
True or false. I'm sure i came across this bit of info on here, but i have been unable to find a reference to it with a search. It was a while ago though.