Dimensions of heat sink?

I'm looking into a cooling mod for my AAO-150, and I was hoping to get some of the dimensions from someone on the forum. Can someone tell me what the exact size of the metal cooling "tray" is, and the clearances?

I was thinking about using something like this:
http://www.dangerden.com/store/ramsinks ... cards.html -- Just sticking a couple of the shorter ones on the "tray".

Thanks!