I am a Jeffries collector, so this is a very exciting find!
The ink signature would be about a $400-$500 signature in a certified cut form. As I look at it I am not sure it is vintage ink. That would need to be investigated. The handwriting at the top does not appear to be Jeffries'. I had a similar item and it was not his. The photo itself is a cabinet card from 1899 that was turned into the artwork. Here is what it looked like:
One question I have is why the mount is still there. If the photo was skinned it would be without mount. Perhaps it is a 2nd generation photo [picture of a picture].
If these are the actual production photos and mock-ups used to make the cards, they are valuable but it is not possible to say how much outside an auction setting. As mounted boxing photos ca. 1909 they would have values in the range of $50, or more depending on condition and subjects. Some of the 'duds' in the set aren't worth much as photos because no one would collect them, but to the right specialty collectors the others would be worth more. Attell and Johnson would command premiums from collectors. Again, you would need to auction them to establish value.
The other photo was from a Fleet Week and was used on a postcard.
The Dana PCs range in value depending on condition and subject matter.
I would love to see more scans. If you have trouble as to where to host them, PM me and perhaps I can help through my web site.
I don't know what you want to do with them. I could certainly make you an offer on them since I collect Jeffries stuff, but I would be taking a SWAG approach since it is impossible to say what they would command at auction. If you want an AH recommendation, I would suggest trying Love of the Game. Al [Crisafulli; he is on the board here] is great to work with and he does not hesitate to ask for boxing guys like me to help when it comes to ID and write-ups. BST [also on board here] just did their first auction and they made a nice showing, plus they advertise big cash advances, so that would be worth considering.
I would love for you to sell them on eBay so I could afford them; in other words, don't do that!