I suppose the problems with using standard headbolts are that the 'standard' bolts are no longer available.
Just thought I'd route through my old bolts box to compare.
Found some with 'KX1000' on them, the rest are waisted 10.9 M12 bolts.

The onset of MLS gaskets does bring this spring effect upon expansion and contraction but will the gasket allow the head to expand if I bolt the head with 12.9 bolts.

I have some debating with myself here. Great to hear points and experience.
Certainly lots of blocks have been cracked but is that because the old fibre gaskets didnt absorb the contraction without failing?

My block is a 205 and I don't believe/won't be buying a 200 block to long stud. It was a 'best fix' in the 90's. The real fix is a through stud block from S&J.

In all my years this is the first MLS gasket separation I have had on my rally car (running 2.4 bar through a restrictor)

I think the bolt tensile strength has been compromised rather than gasket failed.

Hmmmmm reduce CR, reduce boost.