I posted this Link in another post about CCing Cylinder Heads -
http://www.cmc.net/~xero/Mousesporting.html
It is very informative and some of his Photos and drawings are very good.
I know it mainly 'Furd' based discriptions, I stumbled upon it while looking for info on porting my son's 302 (furd), but, the info can be applied to most any head work.
I thought the "Thread Wand" article was really resorcefull - I've seen this done in 'high-buck' racing developement with dies and other indicators - the 'thread' is a good way to get the same information.
Happy reading;

John