The route is described on the Virginia Happy Trails Running Club website:
This run is regarded by many as the ultimate hill workout for big western 100s like Wasatch or Hardrock. Elevations range from 930 feet at the trailhead along the Tye River to 4,063 feet at the Priest’s summit. The run consists of a 14 mile loop of the Appalachian Trail and Mau-Har Trail, which takes you up and over Three Ridges. This is followed by a 9 mile out-and-back up the Priest, whose ascent gains a quad-burning 3,000 feet in just 4 miles. Climbs like this are rare indeed in Virginia.
From the trailhead off of Route 56, take the white-blazed Appalachian Trail (AT) north across the road and across the Tye River, and begin the ascent up Three Ridges. In 2.0 miles, come to the intersection with the Mau-Har Trail (you will return on this trail). Stay on the AT, and enjoy several spectacular views of the Priest before reaching the summit of Three Ridges (3,790 feet) at mile 5.9. Continue on the AT for 2.8 miles, descending to the Mau-Har Trail near Maupin Field Shelter. Take a left onto the blue-blazed Mau-Har Trail for 3.3 miles before intersecting the AT. Take a right on the white-blazed AT and descend 2.0 miles back to your car. This first loop is 14 miles.
The finale is the 3,000 foot ascent of the Priest. Take the white-blazed AT south and climb for the next 4.0 miles before reaching the summit plateau. The turnaround is the turnoff to Priest Shelter.
Dustin Smith and I are doing a mixed team self-supported run tomorrow to get something recorded on the women's side.
Kate did great out there and came out with a women's supported FKT in 8h, 16m!
She sprained her ankle at ~7.5m - nearly ending the day - so was extra ginger/careful (and slower) on the rest. A bit sad since Kate is a freight train on the downs! (And we had just started coming off Three Ridges). Nonetheless, excellent day out at the park.