Nice box!! It looks to be in good shape. Try using WD40 on a spot to see if it helps clean it up. I have used it on some of my old boxes and it has worked well. Also, Kennedy recommends it for their brown wrinkle paint......just keep it away from the decal!
I try not to refinish unless I have to....it's next to impossible to replicate the original paint finish. I have an old SK box which had a similiar texture and couldn't match it. I read somewhere they achieved it by using to different kinds of paint which in todays market would require a good bit of $$ to achieve....at least for me because I'm cheap.