It's always a hard call to make whether to clean or not. You have a $15 coin so the first thing you have to decide is if you can live with loosing $15 in value if all goes wrong. You also have to try to determine if you will be able to see more or less detail when you take the patina off. Sometimes a coin will appear to have less detail when it wasn't crisp to start with and it ends up one solid color. I personally lightly clean lower value coins if I think it will improve their appearance. Sometimes it works and sometimes it doesn't. Just make your own decision when it comes to cleaning. You will get very strong opinions both ways. Nice find though! Still on my bucket list for sure.