Beautiful route. It was my first 25 yrs. ago.
Rivers is a bit of a misnomer for the Phoebe River. Pencil lakes with places where the water falls down to the next pencil lake is a better description.
High water will be a blessing as to travel to Lake Polley. Between Square and Kawasachong Lakes you will need to pull over a couple of beaver dams. There is one larger beaver dam that you will need to portage around as you approach Kawasachong. Higher water will help you avoid the delta into Kawasachong Lake. You should have no trouble as you paddle the Phoebe River between Lake Polley and Hazel Lake.
After you leave Hazel Lake and portage back to the Phoebe River you will soon encounter a rock garden. As you look at it from the seat of your canoe, it appears there is no way through. Especially in low water. However, at satellite view reveals a channel cleared in the rocks.
Head to the northern shore of the river and you should see it.
There is only one spot that may give you a bit of trouble after that. Between Knight Lake and Phoebe Lake there is a narrow channel that has some current. It may require some power strokes in this spot to get through.
Take the longer 280rd. portage from Grace to Beth Lake. The portages through Ella Lake are rocky and often muddy when wet. The longer portage has some ups and downs, but is usually dry with better footing.
Hope you have a great trip.