What is the mounting bolt spacing of a typical toilet tank?
There is no spacing standard, friend. 

Tighten all them by hand first then go around and tighten them until you think its good. You don't wanna tighten too much because it'll break the toilet. After you tighten them check 4 leaks. If it leaks then tighten them. 

The tank will always have a little wobble, unless its installed close to the wall, so you'll want to ensure if its free standing, meaning nothing is bracing it, tighten it to a degree that there is a bit of stiffness in relation to movement and you should be fine.