You can do it, mama!  I've had two amazing VBAC's (planning my third now) - my first was 10 lbs, the second, 10 lbs, 10 oz.  (with no tearing or episiotomy needed)

I think that your preparedness/calmness has more to do with your ability to birth a large baby than anything else.  Make sure you feel safe with your care providers and that they aren't going to be telling you how "large" your baby is during your pregnancy and while you're laboring.  (as a doula, I've seen mothers wind up with c-sections only because the OB felt the baby was too large for the mother to birth).  Negative energy is difficult to work with.  I would also strongly recommend having a doula with you. 

Best wishes for a wonderful birth!