The above diagram shows how the various cooling components will be connected on my R1 installation. It consists of some ideas from the Pro-motive installation manual and my own interpretation of how to modify the R1 head outlet pipes in order to connect a heater matrix.
The main feature I've incorporated is re-configuring the head outlet pipes in a way that allows the heater matrix feed to occur before the thermostat. Much like the standard mini setup. The outlet from the heater matrix is fed back into the cooling system as per the Pro-motive manual.
The central instrument cluster on a classic mini and many classic cars utilize a mechanical voltage regulator (stabilizer) to provide a constant 10v to the instruments. Variance in the supply voltage will cause an internal bimetallic strip to change shape making the internal contacts connect or disconnect ensuring a constant 10v is supplied. Overtime the mechanical nature of the regulator can wear causing failure and an unreliable voltage output. The convenience and cheapness of modern electronics makes it possible to replace the mechanical regulator with a solid state unit i.e. no moving parts.