Jerry,
The oil cooler mods are a consequence of addressing three issues: (1) need for greater oil heat rejection capacity, (2) free up water jacket heat rejection capacity by removing oil heat load, and (3) eliminate a potential reliability issue with the factory heat exchanger, which is inaccessible with the intake installed. Use of an external oil cooler is greatly facilitated by the conversion to dry sump oiling, and the method used in this car to access the internal oil galleries would not work for a stock wet sump system.
It would probably be better with the stock oil system to tie into the external oil filter lines if an auxiliary cooler is needed, but there would need to be bypass capability for operation in cold weather.
Regards, Dick