Having thought on the weeping stud issue I decided to remove the head and all studs before applying a Loctite thread lock and sealant.  First though somebody posted on the AHExp site that my leaking oil challenge might be due to the studs that hold the rocker cover down being a tad too long.  They suggested fitting the cover without a gasket and seeing if it could be bolted up tight without it.  It couldn't so I removed the studs, ran a tap down the threads to extend them and then shortened the studs by a few mm and it seemed to do the job,

I then removed the head which was a mighty big challenge as it is very heavy.

The head studs had a groove cut in them that was of interest, apparently they help prevent them coming undone.

Nice shiny new pistons

The head didn't seem to show any odd signs at first but the block did have this mark leading from the offending stud hole to the outside of the engine.  The gasket appeared to have a crease at this point as well.  I can't imagine how this could have caused the problem though.

With the head cleaned up I could see no faults and it was flat.

Some signs of being machined but not in its recent past.

On refitting the head I came across this fault with one of the pushrods, the end floats up and down.  I'm collecting a replacement tomorrow.