In thinking on this it may be profitable for you to explain a little why it is so important to have a true running no vibration chuck.
1) Vibration is tough on bearings
2) Vibration is tough on cut finish
3) Vibration is tough on the tool cutter edge
4) If vibration is caused by chuck wobble then, for example, if it is wobbling .003 the chucked part will also wobble and the further it stick out the greater the wobble will be.
If you have a true running chuck, and say your bar is chucked up tight and it is .003 offset then that is what it will be at 1" or 6", assuming the bar is not bent
Ken