Hmmm. The book says that the K-38 has the left CTG, but no mention of the right, whereas the K-38 target (different sight, different gun) had both, and was introduced earlier. In all, my hunch—worth less than you paid for it—is that you have a very early K-38 Combat Masterpiece from the end of 1948. But I’m no S&W expert; I just like (and have bought enough of) the guns enough to spring for a book on them.
Either way, I’d sleep easy on a $525 price for that gun. Again, JMO.
And welcome to the K cult. No going back now…