Trentkln27, If you have a 7S cassette presently, you will need a new free hub to fit an 8S+ cassette unless you have a 4.5 mm spacer behind the cassette. Your other option is a new rear wheel or a wheel set.

Doug64's drivetrain is typical of what will be needed to achieve the gearing you'll use while touring; a mountain bike's crank set and RD. You may need to keep your FD if you have less than a 12T difference between the middle and outer chain rings.

Brad