I decided to leave the last jobs on the loom to focus on the cooling system and fitting the radiator. 
My solution is an Escort (OHV) radiator (back to my roots). Mine came from Dave Simms Automotive. They were helpful with accurate measurements and a reasonable price.

To mount the radiator I used some fine B&Q stair nosings alloy angle. This gave me a good start to develop the mounting.

This was as far as I wanted to go ahead of fitting the air cleaner and cooling fan. Having proved my concept I moved onto... The nose cone fitting. Clearly I had done this already but not put it in my blog!