Nickels are the toughest to clean. I have destroyed many of them following internet suggestions. For any key or semi key date I would go no further than a gentle cleaning with soap and water. For the non rare varieties I have found that a very gentle rub with 000 steel wool leaves the patina intact while returning some detail. Be careful with that if you try.... as I have also ruined nickels learning this trick.
Excellent find. I pitted up a 1912-V nickel I found using some of the advice from the internet. More my fault than theirs because I left it in the Worcestershire sauce overnight instead an hour.