COntra - the serial number of your guitar suggests it's not a late 80's model but a 1992 model. The 92 Catalogue states the PGM300's neck dimensions as being those of the original Wizard neck. I'd guess if you PGM's neck feels thinner or flatter, you got that by chance rather than design, most likely from overzealous hand finishing. In 1992 and 1993 when the PGM300 was available to the world market it didn't bear the PGM logo.
The Wizard II profile is slightly fatter and thicker than the original Wizard neck, a shape more like the original JEM neck profile.
The JPM neck shape was based on, I believe, the "Ultra" neck profile a slightly thicker and also narrower neck shape, having a 42mm wide nut instead of the 43mm found on the Wizard/JEM necks