IIRC: The CB750s and other Hondas use the same oil filter assy. (similar anyway) to the 4 banger Wings, and those bikes had oil coolers made by many aftermarket companies. I would think that one of those addapeters should be easy to fit, but due to the location of the lines you might have to use elbows to route the hoses away from the engine. Maybe ebay to locate one?
That said, why do you think you need an oil cooler, or is it just that you 'want' one?
Bill