I shot the original run of .480 Ruger Alaskan and the .454 Casull Alaskan when they came out. For dangerous game, I'd look at the .480 version - now re-issued in a 5-shot. I like bigger/heavier. You won't get much velocity from the .454s in that short barrel, but what a flame! A significant push in the .480, a big bounce in the .454. I did own a 7.5" .454 SRH - loved it - much more comfortable to shoot, even though the velocity picked up a bit. While, considering the Alaskans, the short sight radius and the way it says 'Howdy' when you shoot hurt the follow-ups, that first shot can be 'on the money', just so much for groups! I did load warm .45 Colt-ish loads in .454 brass for that 7.5" SRH - generally, 255gr LSWC/250gr LRNFP @ 1,000 fps. Don't forget - that .454 case takes small rifle primers!
Now, if you want a little bit larger .45 Colt revolver - 9.63" vs 7.63", while it is an ounce or two lighter, consider a S&W 625 Mountain Gun in .45 Colt - great trigger. It'll take SAAMI spec'd .45 Colt plus a bit - but stay clear of the old 'Ruger/TC-only' loads. You can find them for $500-$600 used. My pusher still had a leftover new one from the last run for $669, I think. I liked my .454 SRH - but my first S&W, the 625MG below, displaced it. A second example made my .45 RH and a Bisley BH leave... I am in S&W land now. Of course, there is nothing wrong with a stock 4" 629, either.