Personally, I'd leave on as much stock as possible and attempt to maximize the height of the bubble. If you're over 6', you face the possiblity of having to use thin seat cushions and/or a headset with a very thin band. I believe you can actually "cheat up" the roll bar a little when you mount it on its brackets. Wish I knew that when I built mine.
Terry
RV9A
N323TP