Thanks, very helpful. I might have to let the D-25 dream go because of the skinny neck.
Welcome, Longnose! Never heard of a D25 of any vintage with anything other than 1-11/16 nut although anything's possible, in fact if anything I'd expect any variation in the early '70's to be on the side of
wider not narrower.
That '87 D30 you mentioned may well have had a 1-5/8 nut, there were a few documented here a while back, with a couple having s/n's so close to each other it suggests Guild specifically built at least one batch (6 guitars) with that narrow nut on purpose, when the spec for it was actually 1-11/16 like the vast majority of their dreads and jumbos.
We've also seen discussed over the years the fact that neck profile (depth and shape) can be an important factor in neck feel. Both my Dreads are 1-11/16 nut but the D40's neck is decidedly fatter than the D25's, almost makes it feel like it's got a wider nut.
It's a mistake to assume all Guild necks will be very consistent and similar even during a given "period", although there have been periods when the necks tended to run "fatter" or "skinnier"". The late '80's was a period of necks tending towards "skinnier" profiles.
But in Westerly all necks were given final shaping by hand, so small variations are inevitable. Our "guru" Hans Moust has said it actually surprised him to see how consistent they actually were given that most of that final shaping was done purely by "eyeball".
SO don't give up on early '70's D25's yet.