It is on my to-do list to send you the gpx file; I'll try to get to that tomorrow.
Your mapping of the portage looks correct with respect to the start and end points, but doesn't accurately show the details of the portage in between. Your map (and the Chrisamar map as well) gives the impression that the portage passes north of the tower site whereas the portage actually goes right through the tower site. At the tower site, I was expecting to find a trail / old road approaching from the south. I thrashed around in the bush a little without finding anything.
Your map does not indicate that Jake's trail and the portage intersect at Ghost Lake and indeed they don't. Unfortunately, It doesn't look to be easy to make your way south along the west shore of Ghost Lake to get from the portage to the trail.
The connectivity between the portage and Jake's trail is no big deal, but if it exists, it would give rise to a interesting hiking loop out of Brent. However, such a loop is much longer than Diana and I were prepared to tackle on Monday.
Someday, but probably not this year, I will check out Jake's trail starting at Cedar Lake. The problem with that one is that I don't look forward to the walk along the old rail bed to reach the start.
Let me thank John Connelly for pointing out the existence of the trail from the Brent Road to the Pan Lake / Ghost Lake portage, which makes a hike to the fire tower and Ghost Lake possible --http://www.network54.com/Forum/352882/thread/1315084533/last-1315365248/Back+from+Pan+Lake+%2C+a+paddle+and+a+walkabout+.