whilst we are talking about someone holding the head on reliably (which is not the same as holding someone reliably for head) its worth mentioning that there are more than one breed of long stud - I've had 3. some are designed for a 17mm (approx) hole in the deck and others about 11mm. i've had 2 lengths of 17mm ones and one was about 3mm longer than the other and the short ones don't 'bottom' in the lower part of the block earlier than the shoulder supporting the o ring seal pulls down against the counterbore in the deck. this means that if you torque them into the block as per spec you have now got a distorted block face. burtons supply these of the same length as one set of mine. SCS supply studs of the smaller diameter seal which are longer and the same size as my 11mm ones (prob got em from SCS originally).

also, the 'short' long studs don't engage with a lot of thread length in the block which is a concern given that the block is only cast iron. that said, I've found that once they are thread locked in they are happy to hold correct torque on the nuts without pulling out though I've heard of others who have had the lower threads pull out which sounds like a disaster. the fact that the shoulder hits the counterbore and pulls against it means you have a way of ensuring the thread locker doesn't compact when you put the nuts on the top.

I've posted about this before and when i first discovered this problem 15 tears ago i spoke with Ahmed Bayoo (rip) who was a little confused by what i was saying but the block and studs were machined / supplied by mount tune so i imagine that unless the machinist was having a bad day others will have suffered a similar fate. it would be possible to machine the counterbore further to achieve greater thread engagement at the bottom but that would reduce the dowelled section for aligning the gasket / head which the long stud provides. those that burtons supply are the 17mm shorter variety (as per mountiune) and they have not failed in my engine even though they have caused sleepless nights!

instead of torquing the studs into the block to x/lb, use strong thread locker and a dial gauge to determine the point when the deck starts to deform then back a bit. 30k miles without a problem.