This sounds like an very high quality trip!!! Good for you.
I was in Harrison 2 years ago but bailed out due to severe weather. People go over that pass all the time and the horse packers tell me it's true that men have taken stock over that pass. The top can be loose. I bailed due to rock avalanche activity after a heavy rain. But the day before two guys came down no problem. Once you are down into the upper lakes, cross to the south side of the stream down to Harrison Lakes, once down off the slabs, before the lake, cross to the north side. The trail is pretty good. It's an old trail that stays open due to use. Steep old-style switch backs. Down from the lake it's easy to loose the trail where and avalanche knocked down the trees a some years ago. Cross this swamp to the dry forest on the other side and follow steep switch backs down a while but then turn right and stay high. The trail is pretty course but is still used regularly by the horse packers. You'll traverse north and come down in a large meadow upstream from East Lake. Unless you want to go to Lake Reflection, which I recommend. In that case just bomb straight down the drainage from Harrison lakes or go with whatever looks good. East Lake is supurb. Good camping, bear boxes.
I went through Junction Meadow last month on the High Sierra trail. Your trip sounds like one that I would very much like to do some day.