I used neatsfoot oil on that and let it sit for a couple of days.
Put the dye on heavy and make sure it fills the impressions, wipe off the excess with a damp sponge then a clean paper towel before it dries.
Let it dry then put on a thin coat of tan kote then let that dry.
Paint the letters, a few times and then seal with resolene or super shene.
It's better if you can spray the finishes on, you won't get streaking.