I realize that this is an old thread but I came across it and thought I would add my two-cents worth about replacing the tuners and some other stuff.
I also have a 1967 Guild F212. I got it in a trade in 1970 or 1971. After playing it for a few years, it was stored in a closet for decades and forgotten except for the times my teenage son played it. Ouch! He didn't treat it well and when I finally dug it out and decided to restore it, it needed some serious work. I should mention that I used to build and restore classic period furniture so I am a very experienced woodworker. The headstock was cracked through a few tuners and the Guild headstock veneer was in such bad shape that I removed it. I fixed the cracked head so that it was stronger than new and it is virtually impossible to tell it was ever repaired. I made a new headstock veneer from a blank. I fixed a crack in the back, re-glued a couple braces and I made a new pick guard. With that all done, I stripped the guitar and finished it with many coats of oil using a special process and special mixture of oils that I developed years ago. The guitar came out absolutely beautiful and the top turned a deep rich golden brown from the oil. However, when I strung it up, I realized that the kneck needed to be re-set so I took it to a well-known luthier in my area and he re-set the kneck and did such a fine job that the finish was perfect near the joint and needed no touch-up at all.
As for the tuners, I replaced the orlginal line tuners with Mini Grovers and am glad I did. They are much better tuners than the cheap original line tuners with plastic knobs. They look much better too. The only reason I can understand anyone wanting to replace Grovers with the inferior original tuners is to make the guitar exactly as it came from the factory. I have never understood such logic although I do understand that the value can be greater for some collectors if everything is original (even if it really isn't when parts are replaced with identical parts). If the guitar was an extremely rare and valuable guitar, I could see such concern but not with a nice playing but not extremely valuable or rare guitar like an F212. I am much more interested in functionality and the Grovers (or similar) tuners are simply much better.
That's just my opinion but if I happend to get another Guild F212 with the factory line tuners, the first thing I would do is replace them with Grover Mini-Tuners or similar tuners. It's a big improvement and they look much better. Do you want a guitar that is functionally better and looks better or do you want a guitar of lower overall quality but MIGHT sell for a few bucks more someday to a collector? If I was buying and F212 and had a choice between one with original tuners and one with better tuners, I would pay more for the latter.
I would never even think of replacing the Grovers with the originals. Not for a second. After all, the Grovers are an improvement. The originals were cheaply made and inferior.