Pantograph on the fork crown? That would give a more definitive clue.
I imagine no matter what frame it turns out to be, that it was bought as a frame perhaps (and then built by a PO), but not necessarily.
With GPM drops, perhaps a contract build for Pinarello? Usually GPM drops were reserved for a lower tubing set (tre tubi, Oria, Aelle, etc...).
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1987 Crest C'dale, 1987 Basso Gap, 1992 Rossin EL, 1990 Van Tuyl, 1985 Trek 670, 2003 Pinarello Surprise, 1990ish MBK Atlantique, 1987 Peugeot Isoard, 1987 Nishiki Tri-A, 1981 Faggin, 1996 C'dale M500, 1984 Mercian Pro, 1982 AD SuperLeicht, 1985 Massi ?, 1988 Daccordi Griffe , 1989 Fauxsin MTB, 1981 Ciocc Mockba, 1992 Bianchi Giro, 1977 Colnago Super, 1971 Raleigh Internat'l, 1998 Corratec U+D, 1991 Peugeot Slimestone, 1987 Bianchi Volpe, 1995 Trek 750