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.
Although I am still quite a way off from installing the engine in the car and subsequently plumbing in the cooling system, I have started to think about how I might approach it so that I do all the required fabrication before I paint the engine bay or powder coat the engine frame.