Striper,
The problem with the 45-70 is the factory loadings are pretty weak,for the modern 45-70.If you reload you can make some pretty stout 45-70 loads that would be perfect for the jungles of Oregan.
You can get the 45-70 in a great rifle called the Marlin Guide gun,18 1/2 in barrel,5shot,or you can get a 450 marlin,basicaly it just a souped up 45-70 straight from the factory.
As for your caliber power line,just look up the Federal ammo site,or winchester,or remington.They will show you all the balistics for cartriges in question.
If I was looking for one gun to take everything from deer to elk I would go with a meidium bore like a .284 or 30 cal rife.It's hard to beat a 30-06,280 rem or 7mm Rem Mag.,if you like to have a BIG gun in your cabinet take a look at the .338 win mag.
BBJ

When I went out west, I took Ruger .270, BRN .338 and BLR .358. Took the BLR .358 and Super Red .44 mag if I was going to hunt high. If hunting low, I would use the .270.

270(270wsm) is .277 cal - 130-160gr
7mm rem mag(280 rem, 7mm-08, 7wsm, etc)is .284 cal - 140-175gr
300 win or wsm or 3006 or 308,etc is all .308 cal - 150 - 200 gr

The gr size of bulletsare what is typically used in each caliber for Big game hunting butdependant on the chambering, rifle preferences and game hunted the listcan narrow.

All would be fine. Ipersonally wouldn't buy another 270 as you might as well either tote your exsiting rifle you know and loveif notadd to the collection. I haven't found anything that 7mm rem mag would do here that a 300 would do better, they really are like spliting hairs upto Moose sized game. So IMO either would be a fine choice. If your buying factory ammo no shortage as both are very popular & well established.

I'd suggest getting a .300 magnum or a .30-06 so that you're covered when you finally get to come up here for moose and really big bears. By then you'll be comfortable with it and shoot it well, rather than going through this whole process again and having a new rifle that you're unfamiliar with. While it's certainly do-able, I wouldn't suggest anyone come to Alaska with less than a 30 caliber.

"Beware the man who owns but one rifle for he knows how to shoot it well."

I would get a Ruger Alweather in 350 remington magnum.

99 percent of the factory loads for the 45-70 now adays are smokless powder. I think only the cowboy action loads are black powder and may of those are not either. Garret and Corbon make loads for the modern 45-70 that will take any animal on earth. If you don't reload and still want the thump of the 45-70, go with the 444 Marlin or the 450 Marlin.

30/06 and go huntin

The 270 is my alltime favorite and I have shot several elk with it without any problem. But, I feel the 30-06 is a better elk gun and has the versitility to do whatever you want to do.

You people are BORING! For 8 bills I would buy a used remington 700 long action with a 06 bolt face and build a custom rifle. say 4 bills for the used gun, 3 bills for a match grade barrel, and a hundred for go no go gauges. Throw in a little work and presto chango you've got a custom rifle. Calibers you ask? Will now lets see.....280 ackley, 6.5 x 284 or 338-06. Now you've got not only a rifle but a conversation piece. Live a little folks. the rifle world doesn't start with 270 and end at 30-06.

Browning .300 Win mag.