I do not know the gear ratios, but full size Taylor tuners do fit the mini. I’ve done it. I currently have the full size tuners on with the mini buttons. I did this because I wanted Taylor branded tuners (the mini tuners do not say Taylor on the back), and because the full size tuner buttons seem a little large for my taste on the mini, and I think original mini buttons look better on the smaller mini headstock. Everything worked just fine, simple process.