well, usually blown head gasket won't damage the cylinder head like that
sigh , need to rebuild the engine again
i got 2-3 customer got problem like this. this happen when
1.) head gasket putus and still run the engine and make cylinder head to loose compression.
2.) check torque for cylinder head skru maybe not in spec
3.) need to see top of the block if got sign of compression leaking need to skim the block if not u will get the same problem again.
4.) for the cylinder head u can sent to machine shop for welding alloy and then need to skim.
5.) the metal gasket quality cannot support ur hi comp engine.
6.) i seen ur valve colour not same mean ur compression might not equal to each cylinder. ur a/f ratio will not get perfect each cylinder.
oh well, according to a friend which having same problem like mind , running too rich/lean(i forget which one @_@) will cause the head become like that
it maybe too , look at ur spark plug colour. it look to lean bro.
i build and dyno many near 200hp 4G93 dont have problem like this if u got the correct spec like i mentioned above.