Had the squash back for one week and then the head gasket blew.
It took 10 days to get the head off after stripping the engine of superfluous stuff.
Trouble was the engine is an alloy one and there was reaction between the head studs (Iron) and the alloy of the head.
Had plenty of advice from the 'Plastic pig' club.
1st. Don't use WD40 to infiltrate and soften the gunge - Use PlusGas it is thinner.
2nd. make up a 'stretcher' to aid in lifting the head. This is a piece of iron about 10inches long 2 inches wide and 1/4 inch thick. Drill holes in it to allow the rocker studs to go through it. Put it down over the rocker studs and let it rest on the head studs. Put spacers on it and then gradually screw down on the nuts. The pressure will then lift the head.
We did this and got a good 1/4 inch gap on the spark plug side. NOW plastic is softer than alloy? cut a couple of slips from a piece of plastic around 1/32 inch thick.
Put them into the gap around halfway across the head. Meantime all this while slowly drip plusgas on the head of the studs. Don't flood them it will just run off, but three or four times a day put a couple of drops on the top of the stud. It will gradually make its way down the threads and then into the gap between the stud and the alloy.
Every time you do this take a wooden drift and bang down on first the spark plug side and then the manifold side of the head. I was advised that even if it is only half a millimetre movement this will gradually cause the gunge to let go.
It worked and the head lifted off with no more trouble after a week of this treatment.
Some had said of having to take out the engine and lift it by suspending it, others had said they had had to cut the head off. We managed without taking the engine out just using time and patience.