Well, you need a little bit more than that. You're going to need to make sure that your recoil lug is pinned, otherwise you'll need go, no go gauges and getting the headspace right will be a pain in the rear every time you do a barrel changeout. Also, factory barrels have different threads than custom barrels fit on by most gunsmiths, so if you true the action to accept the 300 WSM barrel, which most will insist on doing, then your 308 barrel won't fit. This means that you would need to get two 30 cal barrels and fit up one for 308 and one for 300 WSM.
You'll also need a sturdy barrel vise, a torque wrench, and an action wrench (like the Type II Surgeon wrench). You'll want to get some nickel anti-sieze to rub on the threads before you snug the barrel down.
Another thing is that 300 WSM takes different mags than a 308. Accurate mag sells them.
