on a 65mm hole your more likely to bend the screwdriver, you'll have about a 30mm radius of sold wood around your centre hole. you could chisel it but its unlikely to leave a nice flat bottom. yes you can do it that way, but i've always been a strong believer in the right tool for the job, and on such a large diameter hole a hole saw is not the right tool.
depending on depth you want to go, and if you have a router, you could hole saw it then use the router to take the centre out. or just get a 65mm forstner bit.
its only a soft wood sleeper, it will snap out easy. aslong as its not on a knot.