Years ago I had a very similar 3” Chief’s Special. In 1955 they were not numbered as a model 36 and just called a Chief’s Special. The 3” barrel adds about 10% more value over the standard 2”. It also appears to be a round butt over the more common square butt configuration for the 3” but doesn’t add value. I recommend soaking it in ATF and acetone. The previously mention cold blue is about the most cost effective measure for attempting to make it look cleaner. You could also have it cerakoted for about $150. Considering it is a $100 revolver in this condition, a $150 cerakote job may be worth it. A 36 with an aftermarket finish with cheap rubber grips is worth about $300.