What is the SN, and we can give an approximate date. For $480, I think you got a good deal. You don't need to remove the side plate to clean it, remove the stocks and just squirt some WD40 or some other grease cutter in behind the trigger and down the hammer slot, and wipe out whatever drips, keep going until it runs fairly clear, then a few drops of some good quality gun oil, and work the action. Unless there is substantial rust, I wouldn't refinish it, that kills collectability. Wear is the gun's life story; that one looks like it had time in a holster.
Here's my M19-3, dates to 1974, SN 7K12168. I gave $800 for it back in 2015. The picture doesn't do it justice.