Hi Paul,
I am not really sure what you have done to the Saracen so far, and was only just aware that it has not been run for 15 years or so. It might be possible that the ignition is retarded, this would make it run hot..........also could be clogged radiator, sticking thermostat, dragging brakes, etc.
Oh and when you drained the sump looking for water.........as the scavenge pump pretty much clears the sump, any water will be in the bottom of the oil tank.
Richard