I have now decided to blank off the heater return pipe, yes I have had another cunning idea, so this part I adapted has now been removed and a 5mm alloy plate has been made and fitted.

I have worked out where all the coolant pipes will go (including the electric pump) and have ordered all the parts to finish, including a remote thermostat - which will be fitted on the engine outlet rather than the inlet.
I will post some pics when the system is finished (y)
ps: I have also decided to fit a Bosch Silver 012 battery, this has 530Amps compared to the 400Amps of the original 063 battery - I need the extra power to crank my high compression engine