Grizz hunting I would imagine is probably the most dangerous hunt most guys will ever go on, this side of the atlantic anyway. Should I ever be fortunate enough to hunt them I would take something much bigger than a 270. No need to limit myself on a once-in-a-lifetime trip. I saw a moose fall to a lesser caliber than a 270 so IMHO good bullet and placement a given your 270 will work fine for anything else.

Scott