I have both, I like the .45 Colt for deer in thick spots or brushy areas, because of the length and weight. Also, I shoot the .45 Colt for plinking also. Keep in mind though that they no longer produce the .45 LC (since 2008), so when they are gone, they're gone. If you're unsure get the colt now and .45-70 later. I use the .45-70 in the early season, when I hunt mostly fields and open areas and it shines for accuracy and power past 100 yards. I do load special .45 Colt rounds using Reloader7 which push the big 300gr. XTP magnum bullets I load a good bit faster than any pistol will send them, making it kind of a mini .45-70. I like carrying the carbine better for much of my hunting though and I carry my .45 Colt New Model Blackhawk for closer off hand/finishing shots, but past 50 yards, I typicall use the carbine.
Unfortunately, due to a data crash haven't got pics of my .45-70 remade, but I love that gun also. Loaded up right, I use it with bullets ranging from round balls up to 405 gr. for a variety of game.
Good luck deciding, but either one is a great weapon.