The factory used a 4 blade direct drive fan in non-AC applications.
When AC was specified a five blade fan with thermo clutch was used. Buick also installed a water pump with extra impellers in AC applications. There is also a difference in the diameter of the drive pulley in addition to an extra belt...and a high capacity alternator. Buick also installed a fan shroud to improve the efficiency of the 5 blade fan when in standing still/low speed situations like stop and go traffic....and a fuel vapor return line to prevent vapor lock in such situations.
Personally, I would want the advantage of the factory AC modifications, or at least the most important ones depending on use and circumstances, if adding an AC system, but that is my opinion.
If you do decide to mimic the factory AC modifications I have all the parts you would need on hand. If interested please send a PM. Good luck!