Put the valves and springs back in, turn head upsidedown, fill the cavities with water and see if there is a leak in an hour or so. I know it sound strange but it seems to work. Water will leak down if there is a gap.
What a nice way to devour a Sunday morning. After several weeks of umm-ing and ah-ing I decided to get some professional help. Not needed!!
I stripped, cleaned and repaired the slave cylinder (helpfully known as the clutch activator in the service manual and parts list)!.
Just need a new gasket for the cover and its done. Followed these instructions:
https://venturers.org/Tech_Library/index.php?action=article&cat_id=001006&id=51&highlight=clutch
and Robert is your mother's brother.