Catch up time then as I haven't reported much recently...
I reinstalled the carbs that Stu had kindly stripped for me and started her up. Things still not very good, but at least it started and sounded better than the last time. Since then, we have gone backwards again - it appears that backwards is the only direction that this s.o.c. likes to go in.
I now have a water leak. A collection of green is pooling on the inlet manifold gasket. There are no splits in any of the hoses so it was decided that the metal pipe (who designed this?!?!) that runs under the manifold must have split somewhere. Nope. Bugger all wrong with it. It's rusty but not poorly.
There was a lot of rusting around the end that goes to the heater so I decided to undo the two bolts. Snap! Coooocccckkkkk! The end of the bolt is now out. I am waiting for Rimmers to deliver a gasket and another bolt before attempting to reconnect the manifold. I am hoping that I have fixed the problem!