Todays purchase was a dull but essential one; 90 degree fittings for the heater core hoses.
After reading this:
VWVortex.com - OEM 90* heater core fitting
I discovered the part number for the fittings to be 1J0 122 291 C but I later found a variant R which had an extra take off that I can use for the cooling of the Tial MV-R:
We'll see how it pans out I guess...