So we took off the head and it was not as bad as we thought it might be and certainly we have dislodged all the muck in the block and the head. I also returned the radiator to the chap who said that he had cleaned it out and repaired the leaks which he clearly had not done!
So next week we will re assemble the motor and try again. Luckily I have a full set of gaskets so it will have a new head and manifold gasket.
Paul Domoney