Any refinish is going to hurt the value, and Czech issue VZ 24's are getting scarce. If not too much blue has been rubbed off, that is probably a place where cold blue will do a good enough job. I depends on what you want to do with the rifle. If you are going to sporterize it anyway, any finish will be fine. If you intend it as part of a collection with little use, the cold blue idea might work fine.