Thank you for the responses! What sparked my interest was a notice I found in an old book last week:
Since my post, I've found this photo of the Pomeroy Tunnel on DPL:
Seems awfully high up on the mountain for a railroad tunnel. I also found this humorous postcard pic:
The tunnel comes out at this location in red on the USGS map, which correlates well with Jeff Young's location:
Also discovered this old newspaper story from an interview with Pomeroy himself:
Here's the west end on Google Earth based on the map in Jeff Ramsey's link:
Again, a fair piece up the hill for a supposed railroad tunnel.
Thank you all,
Matt