In reply to nickhelm2013:
Hi
Your Nepals will be more than fine. I've had two trips to the Andes - one in leather boots (to 6400m) and one in plastics (with inner boot) (to 6900m). If you dress sensibly and the boots aren't too tight, you will be fine.
If you really want another pair, I have the plastics I used (size 10.5) - they're Asolos (can't remember the model) and in good nick.