All good advice above if you use a drill, but if you use a reamer you greatly reduce the risk of chipping, and eliminate blow out.
They will be Much heavier.But I did it and love 'em.
I agree that a vintage style, split shaft tuning machine is excellent medicine EXCEPT
First I am assuming this is 70s style but still a '90s guitar. Those machines are the die cast splits with the diamond shaped stamped steel cover, in chrome, and they're not good IMO at all. You want something like a Gotoh rectangular body split - nickel plate, like a 1966 and older guitar would have.
And to do that, you would want to ream out to 10.0 mm and use conversion bushes, and the Gotohs in the Allparts catalog, TK 0880.