Thanks for the encouragement and comments guys!
Had a few hours this afternoon, so what better way to spend it trying to get the cylinder head off...

.
Anyway, gradual teasing it upwards with heat and oil applied worked - took a while though, but that's how it is with 30 year old fixings. Then I tried to get the remains of the stud out of the head....oh boy..oh boy...oh boy

. Heated it up, sprayed it, heated it up, tried the old two nuts on the stud approach, only managed to mash the threads, tried a pair of mole grips, heated it up...and so on. It is still there, I really don't want to break it as I do not fancy drilling it out and heli coiling it, etc.
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broken stud.jpg [ 149.4 KiB | Viewed 13828 times ]
Might have to weld a nut on and see what that does...
With the head off, this is what I saw...remember, I have not fired this motor up and it has been standing for years...so, the 'goo' is established stuff:
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head off.jpg [ 171.84 KiB | Viewed 13828 times ]
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gunge.jpg [ 144.15 KiB | Viewed 13828 times ]
I am guessing the head gasket had breached between the water and oil galleries. Will have a look in the oil cooler shortly and see if that has also breached. However, the oil itself looked ok - old and dark, but not full of mayonnaise:
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old oil.jpg [ 114.59 KiB | Viewed 13828 times ]
So, I am hoping the ' salad cream goo', is localised, we shall see.
Bores look fine with minimal wear and only tiny surface scores, so that's good, piston crowns are cleaning up fine. Cylinder head looks good, valves appear OK on a cursory inspection. Then the light faded and it was time for a cup of tea

More to follow!