Update:
I used that Silicone-gasket (which is sticky all over)
without any changes (to the gasket) and put it to the engine
Than i put head back on an and reassembly was as expected.
Time-consuming but ok.
Tightened head with 55 ft-lbs.
Engine fired up within a sec an runs smooth again.
No bubbles anymore, even once engine is hot .
No oil in water; No water in oil and nothing leaking to the outside....
Will re-torque bolts twice but i guess, prob is solved.
If i will have to demount the head (someday) again, im
pretty confident, that it will not be a pain again.
I still believe my posting no 23 is correct.
Holes in my head where 12mm without changes.
I drilled to 12,5mm (as such a drill was available)
Even engine is running great now , i would not
oversize as much again. If there ever is a "next time",
i will try 12,3mm ....
Happy motoring
best regards
Christoph
@ Bill : Thank you for your help and confidence.
You are a real friend If you are KRAZY, i want to be Krazy too.
@hardtimes : A little oversize-drilling of the holes will reduce "hardtimes" somewhat
@ Allanw: Thank you for your info, but 55ft-lbs aint much and i
guess Heli-coil will be sufficient here ... (you wont take out the studs
as often as you might take out a spark-plug)