Following discussions I have elected to fit a Thermostatic Oil Cooler Adaptor (TOCA). This is a really neat unit that fits against the engine block and then, with an extended centre threaded spigot, allows the oil filter to be then mounted on the top face of the TOCA.

The advantage is that instead of cold oil being pushed around the whole system and out through the oil cooler matrix well before it reaches anything like warm temperature, a valve in the TOCA keeps the oil within the engine block until it reaches temp the opens the valve to let it flow through cooling matrix.

Slight problem with normal sized filter being tight to get in but working on that.
(Update 28 Jan 2019 – Saw someone looked at this old post so re-read it and wanted to add an update … getting the TOCA on with the oil filter can be a challenge .. don’t worry .. it DOES go on … i think it’s eassier to part screw the inner threaded sleeve into the new filter and then offer this up as a whole ..with the blue TOCA unit .. this helps you get the whole unit in next to the cylinder head)
I can now start to plan the pipe runs and more importantly which angle junction to use to ensure best / easiest run.
Also got to plan how and where I site the cooler itself. This will have to now wait the completion of the top deck and subsequent cowl fitting.