Need help identifying Warren CDV from Spalding Collection

[orator1]

The following CDV on the top left is part of the Spalding Collection at the NYPL. The subject is currently listed as "unidentified". I compared this person to other early 1870s Boston players and was wondering if it could be Sam Jackson, pictured on the top right.
The image at the bottom left is also part of the Spalding Collection and currently unidentified, but I think it has got to be Jackson by comparison. Assuming that is the case, the fact that Jackson shaved his sideburns lends further credence that the CDV could be Jackson.

Similarities:
Hair parted on same side and in same style
Similar amount of forehead showing…hairline is similar
Similar nose, eyes and earlobes
Chin of unidentified player is similar to the woodcut of Jackson.
Mustache size and shape are similar – unidentified player has a “space” in the middle of his moustache under his nose, like the woodcut image.

Differences:
Sideburns are longer in the Jackson photo on the right.
Hair is shorter and slicker in the Jackson photos
The curve in the middle part of the ears is a bit different,
but we're comparing a right ear and a left ear from different angles...
it could be due to asymmetrical facial features.

Thoughts?