Yeah, I wouldn't personally get too hung up on exact ft/lb rating equaling game-taking abilities. Most important is putting the bullet where it will kill and second most important is enough penetration to get to an organ that will result in death. If you're hunting elk and you have a 338 Win Mag or a 6.5x55 with heavy bullets and you tear through the heart and one lung, it's gonna die even though there is a large discrepancy between the energy and velocity between the rounds.
Keeping in mind I've never hunted anything larger than Michigan deer, I'd personally suggest that anthing with a full length (30-06) case with a bore of .277" or .284" or up will be adequate for deer, sheep, goat and most elk with the right bullets. 30-06 comes into it's own at the elk and larger game and as Art suggested, I've heard it's not too difficult to get pretty close to moose so as long as you use a tough bullet, the 30-06 and 7mm Mag and up will probably do just fine. But... if I were to go specifically looking 'large bear' as you put it, I'd want something larger... 338 Win Mag, 35 Whelen or 350 Remington Magnum... something like that. Of course, a 45-70 and a variety of bullets will take care of everything you list if your shots are at about 200 yards or less or if you are good at judging distance and know your trajectory.
In addition to what I've read, I'm good friends with a fellow that hunts moose and elk all the time and my suggestions reflect what he's told me and agree with what I've read. For the large bears, I've been told that you may do fine to go out with a 30-06 or 300 Win Mag looking for a 200 yard shot but the first time you stumble upon a Kodiak and you get within, say, 20 yards of it and it stands up to it's full 10 or 12 feet, you'll think a 460 Weatherby is a bit little for such hunting.
In my opinion, you're asking one rifle to do two rifles jobs, esp not being a hand loader. Something like a 270 or 308 or 7mm-08 is more than ideal for deer, goat and sheep and smaller elk. And for hunting 'large moose' and 'large bear' I'd wanting something in a 35 caliber. 270 is pretty much out for large bear and 350 Rem Mag is way overkill for any deer I've ever seen. You could split the difference and get the 30-06 which is versatile, esp for a handloader, and has served many very well for many years, but it's still more than you need for deer and less than you should probably have for large bear.
Edit - I just re-read your post and for whatever reason, I get the idea you may not have shot a lot of rifles in your time. One thing to keep in mind when comparing some of these cartridges, is recoil can go from 'no problem' to 'whoa, Nelly!' just with the ones in my post. Different people react to recoil in different manners... some folks, it never bothers, others think the 270 is almost punishing. Personally, I'm OK with a standard, non light, weight 300 Win Mag and the 375 H&H is a bit of an eye opener. Never shot a 338 or 35 Whelen but they should be closer to the 300 than the 375.
Just something else to think about. if there's any way you could shoot, say a 30-06 and a 338 Win Mag prior to buying, I might suggest that.
And 30-06 should be adequate for black bear (most that I've ever seen... maybe they grow them bigger up in Canada) but maybe not so much for grizzly.
