Greetings and welcome to the forum, Sean77.

The brief, pre-Model 65 run of .357 Magnum chambered Model 64s probably don't constitute rare by collecting standards, but they are scarce and not encountered often.

If you have the revolver alone, no original box, tools, docs or stocks, and used with some wear-and-tear, it's retains some collecting value as an uncommon model but diminished due to shooter status, probably only $50 to $100 more than what a comparable 64 or 65 from that era would fetch. It's difficult to give a ballpark total number with pictures and a more detailed description of mechanical and cosmetic condition.

There have been a few informative threads on this particular run of 64s; suggest a search to learn a little more, and you might also consider lettering yours to confirm provenance by S&W (and increase value a little).

One suggestion: unless you plan to keep and shoot it forever and genuinely don't care about a future sale, don't refinish it -- that's one of the fastest ways to reduce value.