The 6.5x55 Swede will do everything you want it to and more. A well-placed 6.5mm pill will take down every big game animal in the PACNW with ease.
If a man is going to have only one rifle, it should be a 6.5mm. The 6.5x55 was the main military cartridge of many countries in Europe, therefore, it was and remains popular as a sporting cartridge.
I believe it was Sweden, could have been one of the other countries though, but someone over there had their Fish & Game conduct a study of moose hunts. They found that it didn't matter if the moose was hit with a .375 H&H or a 6.5mm, they all ran about 50 meters before dropping.
I would say to stick with the 6.5x55, and instead of buying another rifle, get yourself set up to reload/handload your own ammo for the 6.5mm.
"To preserve liberty, it is essential that the whole body of the people always possess arms, and be taught alike, especially when young, how to use them." -Richard Henry Lee, Virginia delegate to the Continental Congress, initiator of the Declaration of Independence, and member of the first Senate, which passed the Bill of Rights.