OPL is the prefix to the catalog numbers used for Ovation quad titles in Japan. It is definitely a white label promo as the the letters on top of the record label stand for something like "not for sale"
Ovation in Japan had several titles that i found exactly like this, as white label promo. I never found real releases just these. Harvey Mandel was one i remember. This one also. I recorded this but would have to go take a listen to describe it. But Ovation titles were not very adventurous