Done 50km so far and no sign of pressurisation in the cooling system, so I guess no crack in the head, only time will tell if the HG will hold up. Some observations:
1) all valve clearances were non existent post new HG, suggesting the erling type HG ends up thinner than the MLS.
2) I buggered an injector by turning it anti-clockwise when struggling to remove it, hence undoing the thread in the middle of its body, this sheared the little pins inside resulting in the engine running on 3 cyls post HG replacement. The car would still do over 80k but was well down in power and lumpy on tickover. I managed to bodge a fix to the buggered injector (a small nail was used in place of a broken pin ) and I will order a new injector some time soon).
3) The engine starts MUCH better (it spins over “evenly” on the starter as opposed to go quick/slow, then starts on all 4 instead of 1 then 2 the 3 etc) and it runs MUCH better too, suggesting a leak between cylinders has been affecting the engine for many thousands of miles, but eventually this HG failure progressed to pressurisation and coolant loss.
4) The HG job is generally a PITA …..torquing 18 bolts to 4 different settings takes an hour to do properly, it’s essential to take yr time and carefully note down when each bolt has been torqued to the next setting. I also spent an hour very carefully cleaning the head gasket face (so as not to scratch it), and the same on the block. If I had to do the whole job again I could probably get it done easily in a day.
5) A bit of head warp can PROBABLY be ignored
6) Despite knowing the pitfalls of getting air out of the (completely drained) cooling system, and various tips and tricks it still took me a couple of goes to get all the air out and heater working……great care is needed to get the heater working before test driving the car.
Thanks for the help and encouragement from this forum