I am with Hans (of course), that bridge looks standard to me. i could send you photos of 5 or 6 others that look the same.
plus if the bridge was sanded, the rest of the guitar would likely be in a little better shape, because that would have meant at some point someone cared enough about it to work on it!
i'd call your luthier asap and tell him the bridge appears standard for the period after further research, and you want to keep it, even if it needs removal and reglue.
also Hans would have likely corrected me if I was wrong- its a 1970 "Hoboken design, built in Westerly." 1970 is my favorite year for Guilds (and for the Grateful Dead!)
enjoy the guitar. does it need a neck reset? if so I would do it at the same time as the refret. might not be something u need to repair immediately. I have more than one project instrument on the "back burner." my local luthier is fantastic and inexpensive for most things. but some stuff I would prefer to give to Tom Jacobs at Jacobs Custom guitars. Tom used to work in Westerly in the 70s, and is a master NCL finisher. he is not only authorized for repair by the current Guild guitar company, buy also recommended by them. if you are going to get a refinish (and a neck reset), i'd consider using Jacobs (aka "Fixit" on this forum). He will hand u back a brand new guitar, you wouldn't believe his work.