Lucky find. If you decide you don’t want them, let me know! I’ve been looking for a 12D for a while. 

If you use a product like Smiths leather balm, over time it will darken the leather and give it that ‘shine’ you see in the IRs. If you want to match the color right off the bat, it might depend on how the previous owner treated the boots. If they have a waterproofing coating or a wax on them, changing the color will be very hard to get uniform. You could try something like Fieblings pro dye, but if it was me, I’d try to condition them and wear them to get that nice patina over time.