As tab said this will vary greatly depending on the bolts used.

I recently did the cylinder head on my cosworth with 10.9 grade head bolts (that most suppliers will tell you are genuine or as good as), I simply could not achieve the 180degree final stage. (considering i was using a two foot breaker bar it should have been easy)

So i checked the bolts afterwards to see how tight the 120degree that i managed to get them all to was and it maxed out my torque wrench which goes upto 140nm.

So I think it is safe to say the 10.9 grade bolts dont stretch anything like as much as genuine ford/cosworth bolts and if I had to use them again (which I wont) I would probably be looking to do a 90degree final turn and then once all settled check for 110nm on all bolts.