If it's a milder kit I'll just leave the stock gears. In that case its better to have the torque than the top end.
I did the cheap CIF set on my 70cc. It's 10.49 I think, which has been plenty.
My blue bike with tiny wheelsended up with the 10.49 as well, at least for now. I have a converted single speed that is 7:1 but it's too much. I think I'd be happier with 9.49.