>>793897awesome man, it's really cool!
if you can make a two or three night trip out of it, I'd recommend paddling from the portage site by Beaver Creek Campground on Priest, up against the current through the thoroughfare.
Upper Priest was slightly larger than I was anticipating. But in windy conditions it can still be crossed entirely from south to north in a little over an hour.
The trail that we day hiked is Upper Priest 302. It's 4 miles long from the northern most campground, Trapper. It's some badass old growth forest. Really dense. Not a place I'd like to run into a bear at.
302 ends on a Forest Service road. Head north up the road and you'll eventually run into Upper Priest 308 trail, which follows the Upper Priest River pretty much all the way to Canada. You're right on the edge of Washington and the Salmo-Priest Wilderness, and pretty much in the heart of the southern Selkirks.
I recommend it. Great area.