I checked Greco catalogs from the early 80's but since virtually all the text is Japanese I can't tell what finish they used.
You are right, the finish is most likely Poly. Of course, Poly will be a thicker finish than Nitro so you can generally tell just by looking. If the finish thickness isn't obvious to you, try unscrewing a strap button so you can get a better feel for the thickness of the finish compared to the raw wood surface.
If it were me, I would ask about repairing a poly finish over at the ReRanch refinishing Forum. These guys run a specialty forum on guitar refinishing that I've found quite useful. Check it out here:
Sorry about the damage, sometimes you've just got to live with it. sbStatistics: Posted by VintAxe — Thu Mar 22, 2007 9:29 am
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