I usually don't comment on portrait work, but hey, here I am!
Good info and shot results. data name says Sepia in it, but I commonly do the same with working on previous shots and saving again as a #2 version, unless you've actually toned it so far down to just allow a hint of sepia through, don't know and both would be good anyways.
Here's an experiment to try: Level out the eyes and re-crop. I like the tilt, but I think it would naturally strengthen the intensity on the two in the shot. Another would be to crop the inside halves of each face as a vertical image.
Results could be interesting.

I think this is a wonderful portrait that really captures a feeling, which is the whole point isnt it? Good job.