these are the strange radial marks in number 2 bore..........nb this is the bore that appeared to have been burning ok..

Bleedin' radiator! HELP/discuss pls......
This is number 3 and 4 chambers..note that the h/gasket doesnt line up with water hole in head. Also that both plugs are black and that number 4 chamber is wet.

Bleedin' radiator! HELP/discuss pls......
This is number one and two chambers,look ok.Note water hole alignment.....

Bleedin' radiator! HELP/discuss pls......
Anotheer of the same water hole..

Bleedin' radiator! HELP/discuss pls......
Best guess is that air was getting into no3 and no 4 causing poor burn? All manifold bolts were tight and threads not bottoming out..Gasket shows no sign of blowing..it was one of those shiny gaskets with black pits in it.
COULD be that the inlet manifold is porous on the leg to number 3 and 4?
As for the bore marks,it was hard to get a good pic,tried different cameras and also added more light. But if you look closely ,the marks arent up down,they are radial,with blob marks here and there.They are not connected top/bottom.Although one or two of the blob marks are ovalish perpendicular. The marks have hardly any ridge,they just feel rough to the touch. Is this the very first signs of the piston' picking up',before the marks go top to bottom? I have dragged out from the water jacket holes in the block the liner glue where the residue has hardened and was flapping about in some cases...which is black,but feels like silicone/hylomar.clumps of it.
There are no marks on the h/gasket that show it had blown across any areas,both top and bottom of gasket appeared ok,but there is slight discolouration of the ring round each chamber/liner,but only in areas,not all the way round..