Jack - I am sure others will correct me if I am wrong (very likely), but I do not believe that the
oil cooling tubes in the radiator will stand up to the pressure of your engine
oil - they were designed for much lower pressure trans
oil.
I think you can get water coolers for the oil system that screw in under the oil filter - like a water cooled/heated sandwich plate. Also in the UK I know for sure that there is a range of purpose designed water to oil coolers, called "laminova" or somesuch, try looking on
www.demon-tweeks.com or
www.thinkauto.co.uk
HTH
Wilf