True, the 45/70 will take down a bear, but anything greater than a 30.06 is good for bear. .300 Win Mags are a good bet, as are .375 and a good slug shotgun.
Of course, a strong backup is a good idea too, preferably someone you trust standing behind you to finish the deal if need be.
If a .375 can topple a Cape Buffalo, it can take out a grizz with no problems.
Grizz meat is good too.
[Grizz meat is good too.]
Cook it well - trichinosis is endemic in bears. I treated a fellow who contracted it from eating undercooked grizzly meat. He was in the hospital for 3 weeks and nearly died.