My engine is now bay finally finished, the overheating was caused by the Chinese knock-off fan that came with the car. I therefore bought a quality SPAL fan that solved the problem, along with a Zircotec coated exhaust manifold that kept the under bonnet temperatures down.
The link to my Spider's build progress is here:
http://www.fiatspider.com/f08/viewtopic ... &sk=t&sd=a

Slight welding scar on No 1 pipe to repair a crack.

The new SPAL fan