This is how I remember the kop looking from mid/late 70's until they put the roof on. There's not really a defined area, just an extension of the kop - with a big drop from the top half (possibly explaining 'crows nest').
However, the North/West Corner is pretty much the same shape as it was back then. We called it the triangle...and I still do. Some people call it the cheese wedge, meh. How those names ever got to be used at the North/East corner is beyond me.