We've seen a few factory gold Guilds of the early '50s, but my memory is they were all-gold, rather than just the top. Don't recall seeing a 350/375, but wouldn't shock me to see one. Got a line on one?
I've saw that X-60 ("the golden X-150") several years ago on Craigslist with a different seller and more agreeable price.
Back then I talked to that seller about it and was told the back had been refinished (but thats not in the current description)....
....that said I still have a thing for that guitar.