Need to drill a hole in toilet tank to expand lever
Need tips-drill bit, speed, etc

To be honest it's far easier to go back and buy the correct lever. To drill China you need a carbide hole saw that will cost about $15 for this on time use. It needs a center so you need to plug the existing hole with a dole rod. While drilling you can go at a slow rate but there is a fair chance of breaking the tank.

You're going to drill into vitreous china? Good luck! When the porcelain splinters around the hole contact us and we'll try to locate you a replacement tank.
Take Bals advice and go back and purchase the correct part. Good luck, Tom