More gun than is needed strictly for deer but there is no such thing as overkill. Dead is dead. I've been known to shoot deer with a 375 H&H Mag and a 9.3x62 Mauser. If you're combining deer with an elk hunt then the 300 is a great choice. I'm a believer in carrying a big enough gun to cleanly take the biggest animal you expect to run into.
Take the 300 and enjoy the hunt.