Can you take it apart again and show us some pictures of the block, head and both sides of the gasket? Not sure what we will be able to tell you, but worth a try.
If the block does need skimming by a few thou, label the piston so they go back in the same bores and take them in for skimming too. That will also give a good opportunity to check the bores fully.
I am beginning to think that you may have a cracked head or block, or porosity, so have close scrutiny. I do hope it is something else. You could ask for crack testing prior to skimming. No point paying for a skim if it is a crack.
Yeah im going to take the head off again and will take some close ups of the gasket and block and maybe it will be evident where there was leakage. Im going to strip off this head and save it for when I rebuild another block etc... ive got 4 998cc blocks to choose from and 2/3 gearboxes , so what I will do is take the best block and put it on my best gearbox and go from there , whilst there apart I might aswell use new bearings(inspect crank etc) and get the bores honed, my local guy only charges a £10 for all 4 cylinders.
