I've "overnighted" in Goldendale a number of times while riding around (M/C)... usually at a little family run Motel just west of a pizzeria... Ponderosa Motel. Nice folks there. I remember seeing a cat carcass alongside the road once, north of town (headed north, towards Yakima). Always enjoy ridin' up the curvy road from Mary Hill and Stonehenge as we're comin' into Goldendale.
If you search the Hunting forum, a thread talking about the largest game taken with a 6.8... you'll find a post in there by arteacher where he shares his taking of a black bear with his 6.8 with two shots of a Barnes 110gr load. I'll bet that if you loaded up with the Barnes 95gr TTSX, you'll be fine for either predator you come across. It seems to open very quickly, which should help with the thin skin/soft body of the cat.