Looks good in photos, bridge looks correct (original) for example, looks like ebony bridge and fretboard?
What would be most useful is if seller can provide photos of neck angle. A neck reset on a piece that old may be imminent (or not!), that's the singe biggest potential repair expense affecting value.
A quick primer on checking neck alignment, note it's assumed the bridge height is "as built" for most useful results:
http://www.frets.com/FretsPages/Musician/Guitar/Setup/NeckAngle/neckangle.html
Combined height of bridge and saddle is ideally about 1/2", with about 5/16" being height of bridge from soundboard at top of its arc, the rest being saddle. Saddle height is fine-tuned to give best action along neck. Guild was known to use slightly "thin" bridges at some times and thicker ones at others. Suspect that period could be a "thin" one given Hoboken's rep for light builds, but don't really know.
I do think it's a prime candidate for one of the wide flat necks, though. Should be easy enough to check if the seller's knowledgable enough to measure it. They dated it correctly which is saying something, assuming the seller did the look-up.
Your query regarding history is well advised. Some don't mind an instrument that needs work, having a favored luthier in mind for that work, and others prefer a "no major effort required" or even pristine instrument.
As a general rule of thumb any neckset benefits from not being over-stressed, and although we've seen stories of Guild 12-ers kept strung with
mediums even at standard tension for 40 years with no problems (10 years ago, to be fair), I'd still like to know the instrument was strung up with either lights or mediums tuned down for the bulk of its life.
Other possible "invisible" glitches could be a loose brace or shaved bridge (done in attempt to compensate for a collapsing neck set).
Another thought: If you're worried about somebody potentially swooping in on it before you have a chance to audition it, we're a pretty honorable group here, especially the guys with multi-multiple specimens, and most of the rest of us just kind of live vicariously through them and new members like yourself while enjoying our own little families.
So don't be nervous about posting a seller's link. From what I've seen lately the price might not surprise me, but I don't "follow the market".
Could even be Brazilian, wouldn't surprise me from '65. $3500.00 might even seem like a "reasonable ask" to me if you're looking for that kind of info. But stick around for better-informed opinions, especially if we can get a handle on the neck angle.
And btw there's a member here, Fixit, who used to work at Guild and has a universal 5-star rating for price and quality of work, like, even complete restoration.
If you're willing to ship it to Florida. If it becomes relevant, let us know.