Personally I would want the guide as a back up, armed with maybe a .375 H&H Mag, as a minimum. But I would want my customized S&W 25-5 4" .45 LC on my hip just for comfort. Loaded with 300gr Hornady XTP Mag's or a good 300gr lead hardcast. Your 454 Super Redhawk would do the job, if you are up to it. You have a couple of years to get good with it. Pratice. Start out by trying to hit what you are shooting at, then work up to the speed part. Try and get to were you can get off 6 aimed shot into a 20x20 piece of cardboard at 20-25yds in 8-10 seconds, double action that is. It just might save your skin. You will not have time to thumb the hammer back more than once on a charging grizzlie.